Facilitating Calibration of an Audio Playback Device

ABSTRACT

Example techniques facilitate calibration of a playback device. An example implementation involves a computing device capturing, via a microphone, data representing multiple iterations of a calibration sound as played by a playback device. The computing device identifies multiple sections within the captured data. Two or more sections represent respective iterations of the calibration sound as played by the playback device. Based on the multiple identified sections, the computing device determines a frequency response of the playback device, the frequency response of the playback device representing audio output by the playback device and acoustic characteristics of an environment around the playback device. Based on the frequency response of the playback device and a target frequency response, the computing device determines one or more parameters of an audio processing algorithm and sends, to the playback device, the one or more parameters of the audio processing algorithm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 120 to, and is acontinuation of, U.S. non-provisional patent application Ser. No.16/812,618, filed on Mar. 9, 2020, entitled “Facilitating Calibration ofan Audio Playback Device,” which is incorporated herein by reference inits entirety.

U.S. non-provisional patent application Ser. No. 16/812,618 claimspriority under 35 U.S.C. § 120 to, and is a continuation of, U.S.non-provisional patent application Ser. No. 16/182,886, filed on Nov. 7,2018, entitled “Facilitating Calibration of an Audio Playback Device,”and issued as U.S. Pat. No. 10,585,639 on Mar. 10, 2020, which isincorporated herein by reference in its entirety.

U.S. non-provisional patent application Ser. No. 16/182,886 claimspriority under 35 U.S.C. § 120 to, and is a continuation of, U.S.non-provisional patent application Ser. No. 14/864,393, filed on Sep.24, 2015, entitled “Facilitating Calibration of an Audio PlaybackDevice,” and issued as U.S. Pat. No. 10,127,006 on Nov. 13, 2018, whichis incorporated herein by reference in its entirety.

U.S. non-provisional patent application Ser. No. 14/864,393 claimspriority under 35 U.S.C. § 119 to U.S. Provisional Patent ApplicationNo. 62/220,225, filed on Sep. 17, 2015, the entire contents of which arehereby incorporated by reference in their entirety.

This application hereby incorporates by reference the entire contents ofU.S. patent application Ser. No. 14/481,511, filed on Sep. 9, 2014. Thisapplication also hereby incorporates by reference the entire contents ofU.S. patent application Ser. No. 14/696,014, filed on Apr. 24, 2015.This application also hereby incorporates by reference the entirecontents of U.S. patent application Ser. No. 14/805,140, filed on Jul.21, 2015. This application also hereby incorporates by reference theentire contents of U.S. patent application Ser. No. 14/805,340, filed onJul. 21, 2015. This application also hereby incorporates by referencethe entire contents of U.S. patent application Ser. No. 14/826,873,filed on Aug. 14, 2015.

FIELD OF THE DISCLOSURE

The disclosure is related to consumer goods and, more particularly, tomethods, systems, products, features, services, and other elementsdirected to media playback or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loudsetting were limited until in 2003, when SONOS, Inc. filed for one ofits first patent applications, entitled “Method for Synchronizing AudioPlayback between Multiple Networked Devices,” and began offering a mediaplayback system for sale in 2005. The Sonos Wireless HiFi System enablespeople to experience music from many sources via one or more networkedplayback devices. Through a software control application installed on asmartphone, tablet, or computer, one can play what he or she wants inany room that has a networked playback device. Additionally, using thecontroller, for example, different songs can be streamed to each roomwith a playback device, rooms can be grouped together for synchronousplayback, or the same song can be heard in all rooms synchronously.

Given the ever growing interest in digital media, there continues to bea need to develop consumer-accessible technologies to further enhancethe listening experience.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings where:

FIG. 1 shows an example media playback system configuration in whichcertain embodiments may be practiced;

FIG. 2 shows a functional block diagram of an example playback device;

FIG. 3 shows a functional block diagram of an example control device;

FIG. 4 shows an example controller interface;

FIG. 5 is a flow diagram of an example method;

FIG. 6 is a flow diagram of an example method;

FIG. 7A is a flow diagram of an example method;

FIG. 7B is a flow diagram of an example method;

FIG. 8 is a flow diagram of an example method;

FIG. 9 is a flow diagram of an example method;

FIG. 10A is a flow diagram of an example method;

FIG. 10B is a flow diagram of an example method;

FIG. 11 is a flow diagram of an example method;

FIG. 12 is a flow diagram of an example method;

FIG. 13 shows an example path of a moving microphone;

FIG. 14A shows an example calibration sound;

FIG. 14B shows an example calibration sound;

FIG. 15 shows an example swept component of a calibration sound;

FIG. 16 shows an example noise component of a calibration sound;

FIG. 17 shows an example calibration sound and guard bands;

FIG. 18 shows example calibration sounds and guard bands;

FIG. 19 shows example sections of data in a frequency-domain format;

FIG. 20 shows example calibration sounds and guard bands.

The drawings are for the purpose of illustrating example embodiments,but it is understood that the inventions are not limited to thearrangements and instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

Example procedures for calibrating a playback device may include theplayback device playing one or more calibration sounds that are capturedand/or analyzed by a computing device (e.g., a control device configuredto control the playback device). In some embodiments, the computingdevice may analyze the captured calibration sounds over a calibrationfrequency range of the playback device. Accordingly, the one or morecalibration sounds that are played by the playback device may includefrequencies that span the calibration frequency range. The calibrationfrequency range may include a range of frequencies that the playbackdevice is capable of emitting (e.g., 15-30,000 Hz) and may includefrequencies that are considered to be within the range of human hearing(e.g., 20-20,000 Hz). By playing and subsequently capturing calibrationsounds spanning the calibration frequency range, a frequency responsethat is inclusive of the calibration frequency range may be determinedfor the playback device. Such a frequency response may be representativeof the environment in which the playback device played the calibrationsounds.

An example of such an environment may include a room with walls,ceilings, and/or furniture, and so forth. Such objects within theenvironment may affect a listener's perception of playback by theplayback device in various ways based on where the listener ispositioned within the environment and/or where the playback device ispositioned within the environment. Accordingly, for calibration, theplayback device may be positioned within the environment where theplayback device will later perform playback of audio content that is notnecessarily related to calibration. In that position, the environmentmay affect the calibration sounds played by the playback devicesimilarly to how playback might be affected by the environment duringnormal playback.

Some example calibration procedures may involve the computing devicecapturing, at multiple physical locations, calibration sounds played bythe playback device, which may assist in determining acousticcharacteristics of the environment. To facilitate capturing thecalibration sounds at multiple points within the environment, somecalibration procedures involve a moving microphone. For example, themicrophone (e.g., of the computing device) that captures the calibrationsounds may be continuously moved through the environment while thecalibration sounds are played. Such continuous movement may facilitatecapturing the calibration sounds at multiple physical locations withinthe environment, which may provide a better understanding of how theenvironment affects audio playback by the playback device.

In some embodiments, the playback device may repeatedly play calibrationsounds such that each calibration sound spans the calibration frequencyrange during each repetition. Each calibration sound may be captured bythe microphone of the computing device at a different physical locationwithin the environment, thereby providing an audio sample for eachlocation. Playing and capturing such calibration sounds may thereforefacilitate determining a space-averaged frequency response of theplayback device operating within the environment.

Example calibration sounds may span the calibration frequency rangeusing various waveforms. Some example calibration sounds may includecalibration noise (e.g., pseudorandom periodic noise) that spans atleast a portion of the calibration frequency range. However, phasedistortion caused by the microphone's movement may complicateassociation of captured sounds with emitted calibration noise. Otherexample calibration sounds may include a swept sound (e.g., a swept-sineor chirp) that ascends or descends in frequency through at least aportion of the calibration frequency range. Such a swept sound mayfacilitate association of a captured sound with an emitted swept sound,as the phase shift may take the form of predictable Doppler shift.However, at lower frequencies, a swept sound played at a volumenecessary to overcome background noise typically present in a givenenvironment may overload a speaker driver of the playback device.

As such, some example calibration sounds described herein may include acalibration sound that includes both a first component and a secondcomponent, which may help alleviate some of these issues. For instance,the calibration sound may include a first component that includescalibration noise between a minimum of the calibration frequency range(e.g., 15-20 Hz) and a first threshold frequency (e.g., 50-100 Hz). Thefirst component may be emitted by the playback device with energysufficient to overcome typical background noise (e.g., that of a quietroom) with a lower risk of overloading the speaker driver(s) of theplayback device when compared to emitting a swept sound. The calibrationsound may also include a second component that sweeps through (e.g.,ascends or descends through) frequencies between a second thresholdfrequency (e.g., a frequency within the range of 50-100 Hz) and amaximum frequency of the calibration frequency range (e.g., 20-30,000kHz). Use of a predictable sound, such as the swept sound of the secondcomponent, facilitates the computing device accounting for phasedistortion resulting from the microphone motion.

Since portions of the calibration frequency range may be audible tohumans, some aspects of the calibration sound may be designed to makethe calibration sound more pleasant to a human listener. For instance,some calibration sounds may include a transition frequency range inwhich the first (noise) component and the second (swept) componentoverlap. The first component overlapping the second component infrequency may avoid potentially unpleasant sounds that are associatedwith a harsh frequency transition between the first component and thesecond component. In another example, the second portion of thecalibration sound may descend (rather than ascend) through at least aportion of the calibration frequency range. While either an ascending ordescending second component may be effective for calibration, a soundwith descending frequency may be more pleasant to hear because of theparticular shape of the human ear canal.

In some circumstances, multiple playback devices may be calibratedduring a calibration procedure. For instance, an example calibrationprocedure may involve calibrating a grouping of playback devices. Such agrouping might be a zone of a media playback system that includesmultiple playback devices, or, a grouping might be formed from multiplezones of a media playback system that are grouped into a zone group thatincludes a respective playback device from each zone. Such groupingsmight be physically located within the same environment (e.g., a room ofa house or other building).

In some embodiments, multiple playback devices may play calibrationsounds concurrently. However, when multiple playback devices play thesame calibration sound concurrently, the concurrent calibration soundsmay interfere with one another, which may prevent the microphone of thecomputing device from capturing audio of quality sufficient forcalibration of the multiple playback devices. Further, the computingdevice might not be able to associate a particular calibration soundwith the playback device that played the particular calibration soundbecause common frequencies of the various calibration sounds aregenerally indistinguishable.

Within example implementations, the calibration sounds may be tailoredin an attempt to avoid such interference. For instance, first (noise)components of the calibration sounds played by respective playbackdevices may be lengthened in duration. Second (swept) components of thecalibration sounds played by the respective playback devices may bemutually staggered so that common frequencies of the swept componentsare not played simultaneously by multiple playback devices. Suchlengthening of the respective first components and staggering of therespective second components may provide sufficient time in each cyclefor each of the playback devices to play a respective calibration soundthat is detectable by the computing device. In such examples, the first(noise) components of the calibration sounds might be omitted becausecalibration noise played by the respective playback devices willgenerally be indistinguishable. Accordingly, calibration of the multipleplayback devices may be limited to a frequency range bounded by thesecond threshold frequency and the maximum of the calibration frequencyrange (e.g., the range of frequencies included within the respectivesecond swept components.)

Accordingly, some examples described herein include, among other things,detecting and analyzing calibration sounds that are played by a playbackdevice to determine a frequency response of the playback device that isinfluenced by its surrounding environment, and determining an audioprocessing algorithm tuned to adjust the frequency response of theplayback device to a target frequency response. Other aspects of theexamples will be made apparent in the remainder of the descriptionherein.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a computing device, cause thecomputing device to perform functions. The functions include, as thecomputing device is moving within an environment of a playback device,capturing, via a microphone of the computing device, one or morecalibration sounds played by the playback device. Each of the one ormore calibration sounds includes a sweep through frequencies of acalibration frequency range. The functions further include generatingdata representing the one or more calibration sounds and identifying oneor more sections of the data such that each of the one or more sectionsof the data corresponds to a respective calibration sound of the one ormore calibration sounds. The functions further include using the one ormore sections of the data to determine a frequency response of theplayback device over the calibration frequency range. The frequencyresponse of the playback device characterizes audio playback by theplayback device as influenced by acoustic characteristics of theenvironment of the playback device. The functions further includedetermining one or more parameters of an audio processing algorithmbased on the frequency response of the playback device and a targetfrequency response, and sending, to the playback device, the one or moreparameters of the audio processing algorithm.

In another example, a method performed by a computing device includes,as the computing device is moving within an environment of a playbackdevice, capturing, via a microphone of the computing device, one or morecalibration sounds played by the playback device. Each of the one ormore calibration sounds includes a sweep through frequencies of acalibration frequency range. The method further includes generating datarepresenting the one or more calibration sounds and identifying one ormore sections of the data such that each of the one or more sections ofthe data corresponds to a respective calibration sound of the one ormore calibration sounds. The method further includes using the one ormore sections of the data to determine a frequency response of theplayback device over the calibration frequency range. The frequencyresponse of the playback device characterizes audio playback by theplayback device as influenced by acoustic characteristics of theenvironment of the playback device. The method further includesdetermining one or more parameters of an audio processing algorithmbased on the frequency response of the playback device and a targetfrequency response and sending, to the playback device, the one or moreparameters of the audio processing algorithm.

In another example, a computing device includes one or more processorsand a non-transitory computer-readable medium storing instructions that,when executed by the one or more processors, cause the computing deviceto perform functions. The functions include, as the computing device ismoving within an environment of a playback device, capturing, via amicrophone of the computing device, one or more calibration soundsplayed by the playback device. Each of the one or more calibrationsounds includes a sweep through frequencies of a calibration frequencyrange. The functions further include generating data representing theone or more calibration sounds and identifying one or more sections ofthe data such that each of the one or more sections of the datacorresponds to a respective calibration sound of the one or morecalibration sounds. The functions further include using the one or moresections of the data to determine a frequency response of the playbackdevice over the calibration frequency range. The frequency response ofthe playback device characterizes audio playback by the playback deviceas influenced by acoustic characteristics of the environment of theplayback device. The functions further include determining one or moreparameters of an audio processing algorithm based on the frequencyresponse of the playback device and a target frequency response, andsending, to the playback device, the one or more parameters of the audioprocessing algorithm.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a computing device, cause thecomputing device to perform functions. The functions include capturing,via a microphone of the computing device, one or more calibration soundsplayed by a playback device and generating data representing the one ormore calibration sounds. The functions further include identifying oneor more sections of the data such that each of the one or more sectionsof the data corresponds to a respective calibration sound of the one ormore calibration sounds. The functions further include determining thatmore than a threshold amount of sections of the one or more sections ofthe data correspond to respective signal-to-noise ratios (SNRs) that areless than a threshold signal-to-noise ratio and providing an indication,via a user interface of the computing device, that the playback devicewas not properly calibrated.

In another example, a method performed by a computing device includescapturing, via a microphone of the computing device, one or morecalibration sounds played by a playback device. The method furtherincludes generating data representing the one or more calibration soundsand identifying one or more sections of the data such that each of theone or more sections of the data corresponds to a respective calibrationsound of the one or more calibration sounds. The method further includesdetermining that more than a threshold amount of sections of the one ormore sections of the data correspond to respective signal-to-noiseratios (SNRs) that are less than a threshold signal-to-noise ratio. Themethod further includes providing an indication, via a user interface ofthe computing device, that the playback device was not properlycalibrated.

In another example, a computing device includes one or more processorsand a non-transitory computer-readable medium storing instructions that,when executed by the one or more processors, cause the computing deviceto perform functions. The functions include capturing, via a microphoneof the computing device, one or more calibration sounds played by aplayback device and generating data representing the one or morecalibration sounds. The functions further include identifying one ormore sections of the data such that each of the one or more sections ofthe data corresponds to a respective calibration sound of the one ormore calibration sounds. The functions further include determining thatmore than a threshold amount of sections of the one or more sections ofthe data correspond to respective signal-to-noise ratios (SNRs) that areless than a threshold signal-to-noise ratio and providing an indication,via a user interface of the computing device, that the playback devicewas not properly calibrated.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a computing device, cause thecomputing device to perform functions. The functions include, as thecomputing device is moving within an environment of a first playbackdevice and a second playback device, capturing, via a microphone of thecomputing device, one or more first calibration sounds played by thefirst playback device and one or more second calibration sounds playedby the second playback device. Each of the one or more first calibrationsounds and each of the one or more second calibration sounds includes asweep through frequencies of a calibration frequency range. Thefunctions further include generating data representing the one or morefirst calibration sounds and the one or more second calibration sounds.The functions further include identifying (i) one or more first sectionsof the data such that each of the one or more first sections of the datacorresponds to a respective calibration sound of the one or more firstcalibration sounds and (ii) one or more second sections of the data suchthat each of the one or more second sections of the data correspond to arespective calibration sound of the one or more second calibrationsounds. The functions further include using the one or more firstsections of the data to determine a first frequency response of thefirst playback device over the calibration frequency range. The firstfrequency response characterizes audio playback by the first playbackdevice as influenced by acoustic characteristics of the environment ofthe first playback device and the second playback device. The functionsfurther include using the one or more second sections of the data todetermine a second frequency response of the second playback device overthe calibration frequency range. The second frequency responsecharacterizes audio playback by the second playback device as influencedby the acoustic characteristics of the environment of the first playbackdevice and the second playback device. The functions further includedetermining one or more first parameters of a first audio processingalgorithm based on the first frequency response and a first targetfrequency response and determining one or more second parameters of asecond audio processing algorithm based on the second frequency responseand a second target frequency response. The functions further includesending, to the first playback device, the one or more first parametersof the first audio processing algorithm and sending, to the secondplayback device, the one or more second parameters of the second audioprocessing algorithm.

In another example, a method performed by a computing device includes,as the computing device is moving within an environment of a firstplayback device and a second playback device, capturing, via amicrophone of the computing device, one or more first calibration soundsplayed by the first playback device and one or more second calibrationsounds played by the second playback device. Each of the one or morefirst calibration sounds and each of the one or more second calibrationsounds includes a sweep through frequencies of a calibration frequencyrange. The method further includes generating data representing the oneor more first calibration sounds and the one or more second calibrationsounds. The method further includes identifying (i) one or more firstsections of the data such that each of the one or more first sections ofthe data corresponds to a respective calibration sound of the one ormore first calibration sounds and (ii) one or more second sections ofthe data such that each of the one or more second sections of the datacorrespond to a respective calibration sound of the one or more secondcalibration sounds. The method further includes using the one or morefirst sections of the data to determine a first frequency response ofthe first playback device over the calibration frequency range. Thefirst frequency response characterizes audio playback by the firstplayback device as influenced by acoustic characteristics of theenvironment of the first playback device and the second playback device.The method further includes using the one or more second sections of thedata to determine a second frequency response of the second playbackdevice over the calibration frequency range. The second frequencyresponse characterizes audio playback by the second playback device asinfluenced by the acoustic characteristics of the environment of thefirst playback device and the second playback device. The method furtherincludes determining one or more first parameters of a first audioprocessing algorithm based on the first frequency response and a firsttarget frequency response and determining one or more second parametersof a second audio processing algorithm based on the second frequencyresponse and a second target frequency response. The method furtherincludes sending, to the first playback device, the one or more firstparameters of the first audio processing algorithm and sending, to thesecond playback device, the one or more second parameters of the secondaudio processing algorithm.

In another example, a computing device includes one or more processorsand a non-transitory computer-readable medium storing instructions that,when executed by the one or more processors, cause the computing deviceto perform functions. The functions include, as the computing device ismoving within an environment of a first playback device and a secondplayback device, capturing, via a microphone of the computing device,one or more first calibration sounds played by the first playback deviceand one or more second calibration sounds played by the second playbackdevice. Each of the one or more first calibration sounds and each of theone or more second calibration sounds includes a sweep throughfrequencies of a calibration frequency range. The functions furtherinclude generating data representing the one or more first calibrationsounds and the one or more second calibration sounds. The functionsfurther include identifying (i) one or more first sections of the datasuch that each of the one or more first sections of the data correspondsto a respective calibration sound of the one or more first calibrationsounds and (ii) one or more second sections of the data such that eachof the one or more second sections of the data correspond to arespective calibration sound of the one or more second calibrationsounds. The functions further include using the one or more firstsections of the data to determine a first frequency response of thefirst playback device over the calibration frequency range. The firstfrequency response characterizes audio playback by the first playbackdevice as influenced by acoustic characteristics of the environment ofthe first playback device and the second playback device. The functionsfurther include using the one or more second sections of the data todetermine a second frequency response of the second playback device overthe calibration frequency range. The second frequency responsecharacterizes audio playback by the second playback device as influencedby the acoustic characteristics of the environment of the first playbackdevice and the second playback device. The functions further includedetermining one or more first parameters of a first audio processingalgorithm based on the first frequency response and a first targetfrequency response and determining one or more second parameters of asecond audio processing algorithm based on the second frequency responseand a second target frequency response. The functions further includesending, to the first playback device, the one or more first parametersof the first audio processing algorithm and sending, to the secondplayback device, the one or more second parameters of the second audioprocessing algorithm.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a first computing device, cause thefirst computing device to perform functions. The functions includereceiving, from a second computing device, data representing one or morecalibration sounds that are played by a playback device and captured bythe second computing device. Each of the one or more calibration soundsincludes a sweep through frequencies of a calibration frequency range.The functions further include identifying one or more sections of thedata such that each of the one or more sections of the data correspondsto a respective calibration sound of the one or more calibration sounds.The functions further include using the one or more sections of the datato determine a frequency response of the playback device over thecalibration frequency range. The frequency response of the playbackdevice characterizes audio playback by the playback device as influencedby acoustic characteristics of the environment of the playback device.The functions further include determining one or more parameters of anaudio processing algorithm based on the frequency response of theplayback device and a target frequency response and sending, to theplayback device, the one or more parameters of the audio processingalgorithm.

In another example, a method performed by a first computing deviceincludes receiving, from a second computing device, data representingone or more calibration sounds that are played by a playback device andcaptured by the second computing device. Each of the one or morecalibration sounds includes a sweep through frequencies of a calibrationfrequency range. The method further includes identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. The method further includes using the one or moresections of the data to determine a frequency response of the playbackdevice over the calibration frequency range. The frequency response ofthe playback device characterizes audio playback by the playback deviceas influenced by acoustic characteristics of the environment of theplayback device. The method further includes determining one or moreparameters of an audio processing algorithm based on the frequencyresponse of the playback device and a target frequency response andsending, to the playback device, the one or more parameters of the audioprocessing algorithm.

In another example, a first computing device includes one or moreprocessors and a non-transitory computer-readable medium storinginstructions that, when executed by the one or more processors, causethe first computing device to perform functions. The functions includereceiving, from a second computing device, data representing one or morecalibration sounds that are played by a playback device and captured bythe second computing device. Each of the one or more calibration soundsincludes a sweep through frequencies of a calibration frequency range.The functions further include identifying one or more sections of thedata such that each of the one or more sections of the data correspondsto a respective calibration sound of the one or more calibration sounds.The functions further include using the one or more sections of the datato determine a frequency response of the playback device over thecalibration frequency range. The frequency response of the playbackdevice characterizes audio playback by the playback device as influencedby acoustic characteristics of the environment of the playback device.The functions further include determining one or more parameters of anaudio processing algorithm based on the frequency response of theplayback device and a target frequency response and sending, to theplayback device, the one or more parameters of the audio processingalgorithm.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a first computing device, cause thefirst computing device to perform functions. The functions includereceiving, from a second computing device, data representing one or morecalibration sounds that are played by a playback device and captured bythe second computing device. The functions further include identifyingone or more sections of the data such that each of the one or moresections of the data corresponds to a respective calibration sound ofthe one or more calibration sounds. The functions further includedetermining that more than a threshold amount of sections of the one ormore sections of the data correspond to respective signal-to-noiseratios (SNRs) that are less than a threshold signal-to-noise ratio andsending an indication, to the second computing device, that the playbackdevice was not properly calibrated.

In another example, a method performed by a first computing deviceincludes receiving, from a second computing device, data representingone or more calibration sounds that are played by a playback device andcaptured by the second computing device. The method further includesidentifying one or more sections of the data such that each of the oneor more sections of the data corresponds to a respective calibrationsound of the one or more calibration sounds. The method further includesdetermining that more than a threshold amount of sections of the one ormore sections of the data correspond to respective signal-to-noiseratios (SNRs) that are less than a threshold signal-to-noise ratio andsending an indication, to the second computing device, that the playbackdevice was not properly calibrated.

In another example, a first computing device includes one or moreprocessors and a non-transitory computer-readable medium storinginstructions that, when executed by the one or more processors, causethe first computing device to perform functions. The functions includereceiving, from a second computing device, data representing one or morecalibration sounds that are played by a playback device and captured bythe second computing device. The functions further include identifyingone or more sections of the data such that each of the one or moresections of the data corresponds to a respective calibration sound ofthe one or more calibration sounds. The functions further includedetermining that more than a threshold amount of sections of the one ormore sections of the data correspond to respective signal-to-noiseratios (SNRs) that are less than a threshold signal-to-noise ratio andsending an indication, to the second computing device, that the playbackdevice was not properly calibrated.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a first computing device, cause thefirst computing device to perform functions. The functions includereceiving, from a second computing device, data representing (i) one ormore first calibration sounds that are played by a first playback deviceand captured by the second computing device and (ii) one or more secondcalibration sounds that are played by a second playback device andcaptured by the second computing device. The functions further includeidentifying (i) one or more first sections of the data such that each ofthe one or more first sections of the data correspond to a respectivecalibration sound of the one or more first calibration sounds and (ii)one or more second sections of the data such that each of the one ormore second sections of the data correspond to a respective calibrationsound of the one or more second calibration sounds. The functionsfurther include using the one or more first sections of the data todetermine a first frequency response of the first playback device overthe calibration frequency range. The first frequency responsecharacterizes audio playback by the first playback device as influencedby acoustic characteristics of the environment of the first playbackdevice and the second playback device. The functions further includeusing the one or more second sections of the data to determine a secondfrequency response of the second playback device over the calibrationfrequency range. The second frequency response characterizes audioplayback by the second playback device as influenced by the acousticcharacteristics of the environment of the first playback device and thesecond playback device. The functions further include determining one ormore first parameters of a first audio processing algorithm based on thefirst frequency response and a first target frequency response anddetermining one or more second parameters of a second audio processingalgorithm based on the second frequency response and a second targetfrequency response. The functions further include sending, to the firstplayback device, the one or more first parameters of the first audioprocessing algorithm and sending, to the second playback device, the oneor more second parameters of the second audio processing algorithm.

In another example, a method performed by a first computing deviceincludes receiving, from a second computing device, data representing(i) one or more first calibration sounds that are played by a firstplayback device and captured by the second computing device and (ii) oneor more second calibration sounds that are played by a second playbackdevice and captured by the second computing device. The method furtherincludes identifying (i) one or more first sections of the data suchthat each of the one or more first sections of the data correspond to arespective calibration sound of the one or more first calibration soundsand (ii) one or more second sections of the data such that each of theone or more second sections of the data correspond to a respectivecalibration sound of the one or more second calibration sounds. Themethod further includes using the one or more first sections of the datato determine a first frequency response of the first playback deviceover the calibration frequency range. The first frequency responsecharacterizes audio playback by the first playback device as influencedby acoustic characteristics of the environment of the first playbackdevice and the second playback device. The method further includes usingthe one or more second sections of the data to determine a secondfrequency response of the second playback device over the calibrationfrequency range. The second frequency response characterizes audioplayback by the second playback device as influenced by the acousticcharacteristics of the environment of the first playback device and thesecond playback device. The method further includes determining one ormore first parameters of a first audio processing algorithm based on thefirst frequency response and a first target frequency response anddetermining one or more second parameters of a second audio processingalgorithm based on the second frequency response and a second targetfrequency response. The method further includes sending, to the firstplayback device, the one or more first parameters of the first audioprocessing algorithm and sending, to the second playback device, the oneor more second parameters of the second audio processing algorithm.

In another example, a first computing device includes one or moreprocessors and a non-transitory computer-readable medium storinginstructions that, when executed by the one or more processors, causethe first computing device to perform functions. The functions includereceiving, from a second computing device, data representing (i) one ormore first calibration sounds that are played by a first playback deviceand captured by the second computing device and (ii) one or more secondcalibration sounds that are played by a second playback device andcaptured by the second computing device. The functions further includeidentifying (i) one or more first sections of the data such that each ofthe one or more first sections of the data correspond to a respectivecalibration sound of the one or more first calibration sounds and (ii)one or more second sections of the data such that each of the one ormore second sections of the data correspond to a respective calibrationsound of the one or more second calibration sounds. The functionsfurther include using the one or more first sections of the data todetermine a first frequency response of the first playback device overthe calibration frequency range. The first frequency responsecharacterizes audio playback by the first playback device as influencedby acoustic characteristics of the environment of the first playbackdevice and the second playback device. The functions further includeusing the one or more second sections of the data to determine a secondfrequency response of the second playback device over the calibrationfrequency range. The second frequency response characterizes audioplayback by the second playback device as influenced by the acousticcharacteristics of the environment of the first playback device and thesecond playback device. The functions further include determining one ormore first parameters of a first audio processing algorithm based on thefirst frequency response and a first target frequency response anddetermining one or more second parameters of a second audio processingalgorithm based on the second frequency response and a second targetfrequency response. The functions further include sending, to the firstplayback device, the one or more first parameters of the first audioprocessing algorithm and sending, to the second playback device, the oneor more second parameters of the second audio processing algorithm.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a playback device, cause theplayback device to perform functions. The functions include receiving,from a computing device, data representing one or more calibrationsounds that are played by the playback device and captured by thecomputing device. Each of the one or more calibration sounds includes asweep through frequencies of a calibration frequency range. Thefunctions further include identifying one or more sections of the datasuch that each of the one or more sections of the data corresponds to arespective calibration sound of the one or more calibration sounds. Thefunctions further include using the one or more sections of the data todetermine a frequency response of the playback device over thecalibration frequency range. The frequency response of the playbackdevice characterizes audio playback by the playback device as influencedby acoustic characteristics of the environment of the playback device.The functions further include determining one or more parameters of anaudio processing algorithm based on the frequency response of theplayback device and a target frequency response. The functions furtherinclude playing audio that is processed using the audio processingalgorithm.

In another example, a method performed by a playback device includesreceiving, from a computing device, data representing one or morecalibration sounds that are played by the playback device and capturedby the computing device. Each of the one or more calibration soundsincludes a sweep through frequencies of a calibration frequency range.The method further includes identifying one or more sections of the datasuch that each of the one or more sections of the data corresponds to arespective calibration sound of the one or more calibration sounds. Themethod further includes using the one or more sections of the data todetermine a frequency response of the playback device over thecalibration frequency range. The frequency response of the playbackdevice characterizes audio playback by the playback device as influencedby acoustic characteristics of the environment of the playback device.The method further includes determining one or more parameters of anaudio processing algorithm based on the frequency response of theplayback device and a target frequency response. The method furtherincludes playing audio that is processed using the audio processingalgorithm.

In another example, a playback device includes one or more processorsand a non-transitory computer-readable medium storing instructions that,when executed by the one or more processors, cause the playback deviceto perform functions. The functions include receiving, from a computingdevice, data representing one or more calibration sounds that are playedby the playback device and captured by the computing device. Each of theone or more calibration sounds includes a sweep through frequencies of acalibration frequency range. The functions further include identifyingone or more sections of the data such that each of the one or moresections of the data corresponds to a respective calibration sound ofthe one or more calibration sounds. The functions further include usingthe one or more sections of the data to determine a frequency responseof the playback device over the calibration frequency range. Thefrequency response of the playback device characterizes audio playbackby the playback device as influenced by acoustic characteristics of theenvironment of the playback device. The functions further includedetermining one or more parameters of an audio processing algorithmbased on the frequency response of the playback device and a targetfrequency response. The functions further include playing audio that isprocessed using the audio processing algorithm.

In one example, a non-transitory computer-readable medium storesinstructions that, when executed by a playback device, cause theplayback device to perform functions. The functions include receiving,from a computing device, data representing one or more calibrationsounds that are played by the playback device and captured by thecomputing device. The functions further include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. The functions further include determining that morethan a threshold amount of sections of the one or more sections of thedata correspond to respective signal-to-noise ratios (SNRs) that areless than a threshold signal-to-noise ratio. The functions furtherinclude providing an indication that the playback device was notproperly calibrated.

In another example, a method performed by a playback device includesreceiving, from a computing device, data representing one or morecalibration sounds that are played by the playback device and capturedby the computing device. The method further includes identifying one ormore sections of the data such that each of the one or more sections ofthe data corresponds to a respective calibration sound of the one ormore calibration sounds. The method further includes determining thatmore than a threshold amount of sections of the one or more sections ofthe data correspond to respective signal-to-noise ratios (SNRs) that areless than a threshold signal-to-noise ratio. The method further includesproviding an indication that the playback device was not properlycalibrated.

In another example, a playback device includes one or more processorsand a non-transitory computer-readable medium storing instructions that,when executed by the one or more processors, cause the playback deviceto perform functions. The functions include receiving, from a computingdevice, data representing one or more calibration sounds that are playedby the playback device and captured by the computing device. Thefunctions further include identifying one or more sections of the datasuch that each of the one or more sections of the data corresponds to arespective calibration sound of the one or more calibration sounds. Thefunctions further include determining that more than a threshold amountof sections of the one or more sections of the data correspond torespective signal-to-noise ratios (SNRs) that are less than a thresholdsignal-to-noise ratio. The functions further include providing anindication that the playback device was not properly calibrated.

It will be understood by one of ordinary skill in the art that thisdisclosure includes numerous other embodiments. While some examplesdescribed herein may refer to functions performed by given actors suchas “users” and/or other entities, it should be understood that this isfor purposes of explanation only. The claims should not be interpretedto require action by any such example actor unless explicitly requiredby the language of the claims themselves.

When the terms “substantially” or “about” are used herein, it is meantthat the recited characteristic, parameter, or value need not beachieved exactly, but that deviations or variations, including forexample, tolerances, measurement error, measurement accuracy limitationsand other factors known to those of skill in the art, may occur inamounts that do not preclude the effect the characteristic was intendedto provide.

II. Example Operating Environment

FIG. 1 shows an example configuration of a media playback system 100 inwhich one or more embodiments disclosed herein may be practiced orimplemented. The media playback system 100 as shown is associated withan example home environment having several rooms and spaces, such as forexample, a master bedroom, an office, a dining room, and a living room.As shown in the example of FIG. 1, the media playback system 100includes playback devices 102, 104, 106, 108, 110, 112, 114, 116, 118,120, 122, and 124, control devices 126 and 128, and a wired or wirelessnetwork router 130.

Further discussions relating to the different components of the examplemedia playback system 100 and how the different components may interactto provide a user with a media experience may be found in the followingsections. While discussions herein may generally refer to the examplemedia playback system 100, technologies described herein are not limitedto applications within, among other things, the home environment asshown in FIG. 1. For instance, the technologies described herein may beuseful in environments where multi-zone audio may be desired, such as,for example, a commercial setting like a restaurant, mall or airport, avehicle like a sports utility vehicle (SUV), bus or car, a ship or boat,an airplane, and so on.

a. Example Playback Devices

FIG. 2 shows a functional block diagram of an example playback device200 that may be configured to be one or more of the playback devices102-124 of the media playback system 100 of FIG. 1. The playback device200 may include a processor 202, software components 204, memory 206,audio processing components 208, audio amplifier(s) 210, speaker(s) 212,and a network interface 214 including wireless interface(s) 216 andwired interface(s) 218. In one case, the playback device 200 might notinclude the speaker(s) 212, but rather a speaker interface forconnecting the playback device 200 to external speakers. In anothercase, the playback device 200 may include neither the speaker(s) 212 northe audio amplifier(s) 210, but rather an audio interface for connectingthe playback device 200 to an external audio amplifier or audio-visualreceiver.

In one example, the processor 202 may be a clock-driven computingcomponent configured to process input data according to instructionsstored in the memory 206. The memory 206 may be a tangiblecomputer-readable medium configured to store instructions executable bythe processor 202. For instance, the memory 206 may be data storage thatcan be loaded with one or more of the software components 204 executableby the processor 202 to achieve certain functions. In one example, thefunctions may involve the playback device 200 retrieving audio data froman audio source or another playback device. In another example, thefunctions may involve the playback device 200 sending audio data toanother device or playback device on a network. In yet another example,the functions may involve pairing of the playback device 200 with one ormore playback devices to create a multi-channel audio environment.

Certain functions may involve the playback device 200 synchronizingplayback of audio content with one or more other playback devices.During synchronous playback, a listener will preferably not be able toperceive time-delay differences between playback of the audio content bythe playback device 200 and the one or more other playback devices. U.S.Pat. No. 8,234,395 entitled, “System and method for synchronizingoperations among a plurality of independently clocked digital dataprocessing devices,” which is hereby incorporated by reference, providesin more detail some examples for audio playback synchronization amongplayback devices.

The memory 206 may further be configured to store data associated withthe playback device 200, such as one or more zones and/or zone groupsthe playback device 200 is a part of, audio sources accessible by theplayback device 200, or a playback queue that the playback device 200(or some other playback device) may be associated with. The data may bestored as one or more state variables that are periodically updated andused to describe the state of the playback device 200. The memory 206may also include the data associated with the state of the other devicesof the media system, and shared from time to time among the devices sothat one or more of the devices have the most recent data associatedwith the system. Other embodiments are also possible.

The audio processing components 208 may include one or moredigital-to-analog converters (DAC), an audio preprocessing component, anaudio enhancement component or a digital signal processor (DSP), and soon. In one embodiment, one or more of the audio processing components208 may be a subcomponent of the processor 202. In one example, audiocontent may be processed and/or intentionally altered by the audioprocessing components 208 to produce audio signals. The produced audiosignals may then be provided to the audio amplifier(s) 210 foramplification and playback through speaker(s) 212. Particularly, theaudio amplifier(s) 210 may include devices configured to amplify audiosignals to a level for driving one or more of the speakers 212. Thespeaker(s) 212 may include an individual transducer (e.g., a “driver”)or a complete speaker system involving an enclosure with one or moredrivers. A particular driver of the speaker(s) 212 may include, forexample, a subwoofer (e.g., for low frequencies), a mid-range driver(e.g., for middle frequencies), and/or a tweeter (e.g., for highfrequencies). In some cases, each transducer in the one or more speakers212 may be driven by an individual corresponding audio amplifier of theaudio amplifier(s) 210. In addition to producing analog signals forplayback by the playback device 200, the audio processing components 208may be configured to process audio content to be sent to one or moreother playback devices for playback.

Audio content to be processed and/or played back by the playback device200 may be received from an external source, such as via an audioline-in input connection (e.g., an auto-detecting 3.5 mm audio line-inconnection) or the network interface 214.

The microphone(s) 220 may include an audio sensor configured to convertdetected sounds into electrical signals. The electrical signal may beprocessed by the audio processing components 208 and/or the processor202. The microphone(s) 220 may be positioned in one or more orientationsat one or more locations on the playback device 200. The microphone(s)220 may be configured to detect sound within one or more frequencyranges. In one case, one or more of the microphone(s) 220 may beconfigured to detect sound within a frequency range of audio that theplayback device 200 is capable or rendering. In another case, one ormore of the microphone(s) 220 may be configured to detect sound within afrequency range audible to humans. Other examples are also possible.

The network interface 214 may be configured to facilitate a data flowbetween the playback device 200 and one or more other devices on a datanetwork. As such, the playback device 200 may be configured to receiveaudio content over the data network from one or more other playbackdevices in communication with the playback device 200, network deviceswithin a local area network, or audio content sources over a wide areanetwork such as the Internet. In one example, the audio content andother signals transmitted and received by the playback device 200 may betransmitted in the form of digital packet data containing an InternetProtocol (IP)-based source address and IP-based destination addresses.In such a case, the network interface 214 may be configured to parse thedigital packet data such that the data destined for the playback device200 is properly received and processed by the playback device 200.

As shown, the network interface 214 may include wireless interface(s)216 and wired interface(s) 218. The wireless interface(s) 216 mayprovide network interface functions for the playback device 200 towirelessly communicate with other devices (e.g., other playbackdevice(s), speaker(s), receiver(s), network device(s), control device(s)within a data network the playback device 200 is associated with) inaccordance with a communication protocol (e.g., any wireless standardincluding IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4Gmobile communication standard, and so on). The wired interface(s) 218may provide network interface functions for the playback device 200 tocommunicate over a wired connection with other devices in accordancewith a communication protocol (e.g., IEEE 802.3). While the networkinterface 214 shown in FIG. 2 includes both wireless interface(s) 216and wired interface(s) 218, the network interface 214 may in someembodiments include only wireless interface(s) or only wiredinterface(s).

In one example, the playback device 200 and one other playback devicemay be paired to play two separate audio components of audio content.For instance, playback device 200 may be configured to play a leftchannel audio component, while the other playback device may beconfigured to play a right channel audio component, thereby producing orenhancing a stereo effect of the audio content. The paired playbackdevices (also referred to as “bonded playback devices”) may further playaudio content in synchrony with other playback devices.

In another example, the playback device 200 may be sonicallyconsolidated with one or more other playback devices to form a single,consolidated playback device. A consolidated playback device may beconfigured to process and reproduce sound differently than anunconsolidated playback device or playback devices that are paired,because a consolidated playback device may have additional speakerdrivers through which audio content may be rendered. For instance, ifthe playback device 200 is a playback device designed to render lowfrequency range audio content (i.e. a subwoofer), the playback device200 may be consolidated with a playback device designed to render fullfrequency range audio content. In such a case, the full frequency rangeplayback device, when consolidated with the low frequency playbackdevice 200, may be configured to render only the mid and high frequencycomponents of audio content, while the low frequency range playbackdevice 200 renders the low frequency component of the audio content. Theconsolidated playback device may further be paired with a singleplayback device or yet another consolidated playback device.

By way of illustration, SONOS, Inc. presently offers (or has offered)for sale certain playback devices including a “PLAY:1,” “PLAY:3,”“PLAY:5,” “PLAYBAR,” “CONNECT:AMP,” “CONNECT,” and “SUB.” Any otherpast, present, and/or future playback devices may additionally oralternatively be used to implement the playback devices of exampleembodiments disclosed herein. Additionally, it is understood that aplayback device is not limited to the example illustrated in FIG. 2 orto the SONOS product offerings. For example, a playback device mayinclude a wired or wireless headphone. In another example, a playbackdevice may include or interact with a docking station for personalmobile media playback devices. In yet another example, a playback devicemay be integral to another device or component such as a television, alighting fixture, or some other device for indoor or outdoor use.

b. Example Playback Zone Configurations

Referring back to the media playback system 100 of FIG. 1, theenvironment may have one or more playback zones, each with one or moreplayback devices. The media playback system 100 may be established withone or more playback zones, after which one or more zones may be added,or removed to arrive at the example configuration shown in FIG. 1. Eachzone may be given a name according to a different room or space such asan office, bathroom, master bedroom, bedroom, kitchen, dining room,living room, and/or balcony. In one case, a single playback zone mayinclude multiple rooms or spaces. In another case, a single room orspace may include multiple playback zones.

As shown in FIG. 1, the balcony, dining room, kitchen, bathroom, office,and bedroom zones each have one playback device, while the living roomand master bedroom zones each have multiple playback devices. In theliving room zone, playback devices 104, 106, 108, and 110 may beconfigured to play audio content in synchrony as individual playbackdevices, as one or more bonded playback devices, as one or moreconsolidated playback devices, or any combination thereof. Similarly, inthe case of the master bedroom, playback devices 122 and 124 may beconfigured to play audio content in synchrony as individual playbackdevices, as a bonded playback device, or as a consolidated playbackdevice.

In one example, one or more playback zones in the environment of FIG. 1may each be playing different audio content. For instance, the user maybe grilling in the balcony zone and listening to hip hop music beingplayed by the playback device 102 while another user may be preparingfood in the kitchen zone and listening to classical music being playedby the playback device 114. In another example, a playback zone may playthe same audio content in synchrony with another playback zone. Forinstance, the user may be in the office zone where the playback device118 is playing the same rock music that is being played by playbackdevice 102 in the balcony zone. In such a case, playback devices 102 and118 may be playing the rock music in synchrony such that the user mayseamlessly (or at least substantially seamlessly) enjoy the audiocontent that is being played out-loud while moving between differentplayback zones. Synchronization among playback zones may be achieved ina manner similar to that of synchronization among playback devices, asdescribed in previously referenced U.S. Pat. No. 8,234,395.

As suggested above, the zone configurations of the media playback system100 may be dynamically modified, and in some embodiments, the mediaplayback system 100 supports numerous configurations. For instance, if auser physically moves one or more playback devices to or from a zone,the media playback system 100 may be reconfigured to accommodate thechange(s). For instance, if the user physically moves the playbackdevice 102 from the balcony zone to the office zone, the office zone maynow include both the playback device 118 and the playback device 102.The playback device 102 may be paired or grouped with the office zoneand/or renamed if so desired via a control device such as the controldevices 126 and 128. On the other hand, if the one or more playbackdevices are moved to a particular area in the home environment that isnot already a playback zone, a new playback zone may be created for theparticular area.

Further, different playback zones of the media playback system 100 maybe dynamically combined into zone groups or split up into individualplayback zones. For instance, the dining room zone and the kitchen zone114 may be combined into a zone group for a dinner party such thatplayback devices 112 and 114 may render audio content in synchrony. Onthe other hand, the living room zone may be split into a television zoneincluding playback device 104, and a listening zone including playbackdevices 106, 108, and 110, if the user wishes to listen to music in theliving room space while another user wishes to watch television.

c. Example Control Devices

FIG. 3 shows a functional block diagram of an example control device 300that may be configured to be one or both of the control devices 126 and128 of the media playback system 100. As shown, the control device 300may include a processor 302, memory 304, a network interface 306, and auser interface 308. In one example, the control device 300 may be adedicated controller for the media playback system 100. In anotherexample, the control device 300 may be a network device on which mediaplayback system controller application software may be installed, suchas for example, an iPhone™, iPad™ or any other smart phone, tablet ornetwork device (e.g., a networked computer such as a PC or Mac™)

The processor 302 may be configured to perform functions relevant tofacilitating user access, control, and configuration of the mediaplayback system 100. The memory 304 may be configured to storeinstructions executable by the processor 302 to perform those functions.The memory 304 may also be configured to store the media playback systemcontroller application software and other data associated with the mediaplayback system 100 and the user.

The microphone(s) 310 may include an audio sensor configured to convertdetected sounds into electrical signals. The electrical signal may beprocessed by the processor 302. In one case, if the control device 300is a device that may also be used as a means for voice communication orvoice recording, one or more of the microphone(s) 310 may be amicrophone for facilitating those functions. For instance, the one ormore of the microphone(s) 310 may be configured to detect sound within afrequency range that a human is capable of producing and/or a frequencyrange audible to humans. Other examples are also possible.

In one example, the network interface 306 may be based on an industrystandard (e.g., infrared, radio, wired standards including IEEE 802.3,wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.15, 4G mobile communication standard, and so on). Thenetwork interface 306 may provide a means for the control device 300 tocommunicate with other devices in the media playback system 100. In oneexample, data and information (e.g., such as a state variable) may becommunicated between control device 300 and other devices via thenetwork interface 306. For instance, playback zone and zone groupconfigurations in the media playback system 100 may be received by thecontrol device 300 from a playback device or another network device, ortransmitted by the control device 300 to another playback device ornetwork device via the network interface 306. In some cases, the othernetwork device may be another control device.

Playback device control commands such as volume control and audioplayback control may also be communicated from the control device 300 toa playback device via the network interface 306. As suggested above,changes to configurations of the media playback system 100 may also beperformed by a user using the control device 300. The configurationchanges may include adding/removing one or more playback devices to/froma zone, adding/removing one or more zones to/from a zone group, forminga bonded or consolidated player, separating one or more playback devicesfrom a bonded or consolidated player, among others. Accordingly, thecontrol device 300 may sometimes be referred to as a controller, whetherthe control device 300 is a dedicated controller or a network device onwhich media playback system controller application software isinstalled.

The user interface 308 of the control device 300 may be configured tofacilitate user access and control of the media playback system 100, byproviding a controller interface such as the controller interface 400shown in FIG. 4. The controller interface 400 includes a playbackcontrol region 410, a playback zone region 420, a playback status region430, a playback queue region 440, and an audio content sources region450. The user interface 400 as shown is just one example of a userinterface that may be provided on a network device such as the controldevice 300 of FIG. 3 (and/or the control devices 126 and 128 of FIG. 1)and accessed by users to control a media playback system such as themedia playback system 100. Other user interfaces of varying formats,styles, and interactive sequences may alternatively be implemented onone or more network devices to provide comparable control access to amedia playback system.

The playback control region 410 may include selectable (e.g., by way oftouch or by using a cursor) icons to cause playback devices in aselected playback zone or zone group to play or pause, fast forward,rewind, skip to next, skip to previous, enter/exit shuffle mode,enter/exit repeat mode, enter/exit cross fade mode. The playback controlregion 410 may also include selectable icons to modify equalizationsettings, and playback volume, among other possibilities.

The playback zone region 420 may include representations of playbackzones within the media playback system 100. In some embodiments, thegraphical representations of playback zones may be selectable to bringup additional selectable icons to manage or configure the playback zonesin the media playback system, such as a creation of bonded zones,creation of zone groups, separation of zone groups, and renaming of zonegroups, among other possibilities.

For example, as shown, a “group” icon may be provided within each of thegraphical representations of playback zones. The “group” icon providedwithin a graphical representation of a particular zone may be selectableto bring up options to select one or more other zones in the mediaplayback system to be grouped with the particular zone. Once grouped,playback devices in the zones that have been grouped with the particularzone will be configured to play audio content in synchrony with theplayback device(s) in the particular zone. Analogously, a “group” iconmay be provided within a graphical representation of a zone group. Inthis case, the “group” icon may be selectable to bring up options todeselect one or more zones in the zone group to be removed from the zonegroup. Other interactions and implementations for grouping andungrouping zones via a user interface such as the user interface 400 arealso possible. The representations of playback zones in the playbackzone region 420 may be dynamically updated as playback zone or zonegroup configurations are modified.

The playback status region 430 may include graphical representations ofaudio content that is presently being played, previously played, orscheduled to play next in the selected playback zone or zone group. Theselected playback zone or zone group may be visually distinguished onthe user interface, such as within the playback zone region 420 and/orthe playback status region 430. The graphical representations mayinclude track title, artist name, album name, album year, track length,and other relevant information that may be useful for the user to knowwhen controlling the media playback system via the user interface 400.

The playback queue region 440 may include graphical representations ofaudio content in a playback queue associated with the selected playbackzone or zone group. In some embodiments, each playback zone or zonegroup may be associated with a playback queue containing informationcorresponding to zero or more audio items for playback by the playbackzone or zone group. For instance, each audio item in the playback queuemay comprise a uniform resource identifier (URI), a uniform resourcelocator (URL) or some other identifier that may be used by a playbackdevice in the playback zone or zone group to find and/or retrieve theaudio item from a local audio content source or a networked audiocontent source, possibly for playback by the playback device.

In one example, a playlist may be added to a playback queue, in whichcase information corresponding to each audio item in the playlist may beadded to the playback queue. In another example, audio items in aplayback queue may be saved as a playlist. In a further example, aplayback queue may be empty, or populated but “not in use” when theplayback zone or zone group is playing continuously streaming audiocontent, such as Internet radio that may continue to play untilotherwise stopped, rather than discrete audio items that have playbackdurations. In an alternative embodiment, a playback queue can includeInternet radio and/or other streaming audio content items and be “inuse” when the playback zone or zone group is playing those items. Otherexamples are also possible.

When playback zones or zone groups are “grouped” or “ungrouped,”playback queues associated with the affected playback zones or zonegroups may be cleared or re-associated. For example, if a first playbackzone including a first playback queue is grouped with a second playbackzone including a second playback queue, the established zone group mayhave an associated playback queue that is initially empty, that containsaudio items from the first playback queue (such as if the secondplayback zone was added to the first playback zone), that contains audioitems from the second playback queue (such as if the first playback zonewas added to the second playback zone), or a combination of audio itemsfrom both the first and second playback queues. Subsequently, if theestablished zone group is ungrouped, the resulting first playback zonemay be re-associated with the previous first playback queue, or beassociated with a new playback queue that is empty or contains audioitems from the playback queue associated with the established zone groupbefore the established zone group was ungrouped. Similarly, theresulting second playback zone may be re-associated with the previoussecond playback queue, or be associated with a new playback queue thatis empty, or contains audio items from the playback queue associatedwith the established zone group before the established zone group wasungrouped. Other examples are also possible.

Referring back to the user interface 400 of FIG. 4, the graphicalrepresentations of audio content in the playback queue region 440 mayinclude track titles, artist names, track lengths, and other relevantinformation associated with the audio content in the playback queue. Inone example, graphical representations of audio content may beselectable to bring up additional selectable icons to manage and/ormanipulate the playback queue and/or audio content represented in theplayback queue. For instance, a represented audio content may be removedfrom the playback queue, moved to a different position within theplayback queue, or selected to be played immediately, or after anycurrently playing audio content, among other possibilities. A playbackqueue associated with a playback zone or zone group may be stored in amemory on one or more playback devices in the playback zone or zonegroup, on a playback device that is not in the playback zone or zonegroup, and/or some other designated device.

The audio content sources region 450 may include graphicalrepresentations of selectable audio content sources from which audiocontent may be retrieved and played by the selected playback zone orzone group. Discussions pertaining to audio content sources may be foundin the following section.

d. Example Audio Content Sources

As indicated previously, one or more playback devices in a zone or zonegroup may be configured to retrieve for playback audio content (e.g.according to a corresponding URI or URL for the audio content) from avariety of available audio content sources. In one example, audiocontent may be retrieved by a playback device directly from acorresponding audio content source (e.g., a line-in connection). Inanother example, audio content may be provided to a playback device overa network via one or more other playback devices or network devices.

Example audio content sources may include a memory of one or moreplayback devices in a media playback system such as the media playbacksystem 100 of FIG. 1, local music libraries on one or more networkdevices (such as a control device, a network-enabled personal computer,or a networked-attached storage (NAS), for example), streaming audioservices providing audio content via the Internet (e.g., the cloud), oraudio sources connected to the media playback system via a line-in inputconnection on a playback device or network devise, among otherpossibilities.

In some embodiments, audio content sources may be regularly added orremoved from a media playback system such as the media playback system100 of FIG. 1. In one example, an indexing of audio items may beperformed whenever one or more audio content sources are added, removedor updated. Indexing of audio items may involve scanning foridentifiable audio items in all folders/directory shared over a networkaccessible by playback devices in the media playback system, andgenerating or updating an audio content database containing metadata(e.g., title, artist, album, track length, among others) and otherassociated information, such as a URI or URL for each identifiable audioitem found. Other examples for managing and maintaining audio contentsources may also be possible.

The above discussions relating to playback devices, controller devices,playback zone configurations, and media content sources provide onlysome examples of operating environments within which functions andmethods described below may be implemented. Other operating environmentsand configurations of media playback systems, playback devices, andnetwork devices not explicitly described herein may also be applicableand suitable for implementation of the functions and methods.

III. Example Methods and Systems Related to Facilitating Calibration ofan Audio Playback Device

As discussed above, some examples described herein include, among otherthings, detecting and analyzing calibration sounds that are played by aplayback device to determine a frequency response of the playback devicein its surrounding environment, and determining an audio processingalgorithm tuned to adjust the frequency response of the playback deviceto a target frequency response. Other aspects of the examples will bemade apparent in the remainder of the description herein.

Methods 500, 600, 700, 800, 900, 1000, 1100, and 1200 respectively shownin FIGS. 5, 6, 7A and 7B, 8, 9, 10A and 10B, 11, and 12 present examplemethods that can be implemented within an operating environmentincluding, for example, one or more of the media playback system 100 ofFIG. 1, one or more of the playback device 200 of FIG. 2, and one ormore of the control device 300 of FIG. 3. The methods 500-1200 mayinvolve other devices as well. Methods 500-1200 may include one or moreoperations, functions, or actions as illustrated by one or more ofblocks 502, 504, 506, 508, 510, 512, 602, 604, 606, 608, 610, 702, 704,706, 708, 710, 712, 714, 716, 718, 802, 804, 806, 808, 810, 902, 904,906, 908, 1002, 1004, 1006, 1008, 1010, 1012, 1014, 1102, 1104, 1106,1108, 1110, 1202, 1204, 1206, and 1208. Although the blocks areillustrated in sequential order, these blocks may also be performed inparallel, and/or in a different order than those described herein. Also,the various blocks may be combined into fewer blocks, divided intoadditional blocks, and/or removed based upon the desired implementation.

In addition, for the methods 500-1200 and other processes and methodsdisclosed herein, the flowcharts show functionality and operation of onepossible implementation of present embodiments. In this regard, eachblock may represent a module, a segment, or a portion of program code,which includes one or more instructions executable by a processor forimplementing specific logical functions or steps in the process. Theprogram code may be stored on any type of computer-readable medium, forexample, such as a storage device including a disk(s) or hard drive(s).In some embodiments, the program code may be stored in memory (e.g.,disks or disk arrays) associated with and/or connected to a serversystem that makes the program code available for download (e.g., anapplication store or other type of server system) to desktop/laptopcomputers, smart phones, tablet computers, or other types of computingdevices. The computer-readable medium may include non-transitorycomputer-readable media, for example, such as computer-readable mediathat stores data for short periods of time like register memory,processor cache, and Random Access Memory (RAM). The computer-readablemedium may also include non-transitory media, such as secondary orpersistent long-term storage, like read-only memory (ROM), optical ormagnetic disks, compact-disc read-only memory (CD-ROM), for example. Thecomputer-readable media may also be any other volatile or non-volatilestorage systems. The computer-readable medium may be considered acomputer-readable storage medium, for example, or a tangible storagedevice. In addition, for the methods 500-1200 and other processes andmethods disclosed herein, each block in FIGS. 5-12 may representcircuitry that is wired to perform the specific logical functions in theprocess.

In some examples, the method 500 is performed by a computing devicetaking the form of a control device, such as the control device 300, butother examples are possible. As such, in the context of the method 500,the computing device may also be referred to herein as a control device.The method 500 may generally include the use of the computing device tocalibrate a playback device.

At block 502, the method 500 may include, as the computing device ismoving within an environment of the playback device, capturing, via amicrophone of the computing device, one or more calibration soundsplayed by the playback device.

To illustrate movement of the computing device during calibration, FIG.13 shows media playback system 100 of FIG. 1. FIG. 13 shows a path 1300along which the computing device (e.g., control device 126) might bemoved during calibration. The control device 126 may indicate (e.g., viaa user interface) how to perform such movement in various ways, such asby way of a video, animation, and/or audible instructions, among otherexamples.

The control device 126 may capture, via a microphone, calibration soundsplayed by a playback device (e.g., playback device 108) at variouspoints along the path 1300 (e.g., at point 1302 and/or point 1304).Alternatively, the control device 126 may capture the calibration soundsalong the path 1300. In some embodiments, the playback device 108 mayplay periodic calibration sounds such that the control device 126captures respective instances of the calibration sound at differentpoints along the path. Comparison of such captured calibration soundsmay indicate how acoustic characteristics of the environment change fromone physical location to another, which may influence parameters of anaudio processing algorithm chosen for the playback device in thatenvironment.

In this context, each of the one or more calibration sounds played bythe playback device may include a sweep through frequencies of acalibration frequency range. For example, the calibration sounds mayeach include a swept sine or another sound that includes a sequence ofall frequencies of the calibration frequency range. While there are aninfinite number of frequencies between any two frequencies, in practice,the calibration sound may include only a sequence of discretefrequencies at a given frequency resolution. Such a collection ofdiscrete frequencies may approximate a continuous sweep through allfrequencies of the calibration frequency range.

In a more specific example, a calibration sound played by the playbackdevice may include a first component that includes (i) calibration noiseat frequencies between a minimum of the calibration frequency range anda first threshold frequency and (ii) a second component that sweepsthrough frequencies between a second threshold frequency and a maximumof the calibration frequency range.

FIGS. 14A and 14B illustrate components of example calibration sounds1400 and 1450 that span respective calibration frequency ranges. In FIG.14A, the calibration frequency range is defined by a minimum frequencyat 1406A and a maximum frequency at 1412A. FIG. 14A illustrates a firstcomponent 1402A (i.e., a noise component) and a second component 1404A(i.e., a “swept” component) of the calibration sound 1400. Component1402A includes pseudo-random noise similar to brown noise (discussedbelow) and spans frequencies from a minimum frequency 1406A (e.g. 15-20Hz) to a first threshold frequency 1408A (e.g., 50-100 Hz). Component1404A includes a swept sine that spans frequencies from a secondthreshold frequency 1410A (e.g., 50-100 Hz) to a maximum frequency 1412A(e.g., 20-30 kHz). As shown, the threshold frequency 1408A and thethreshold frequency 1410A may be the same frequency.

In FIG. 14B, the calibration frequency range is defined by a minimumfrequency at 1406B and a maximum frequency at 1412B. FIG. 14Billustrates a first component 1402B (i.e., a noise component) and asecond component 1404B (i.e., a “swept” component) of an examplecalibration sound 1450. Component 1402B includes pseudo-random noisesimilar to brown noise (discussed below) and spans frequencies from aminimum frequency 1406B to a first threshold frequency 1408A. Component1404A includes a swept sine that spans frequencies from a secondthreshold frequency 1410B to a maximum frequency 1412B. As shown, thethreshold frequency 1410B is a lower frequency than threshold frequency1408B such that component 1402B and component 1404B overlap in atransition frequency range that extends from threshold frequency 1410Bto threshold frequency 1408B.

A swept component (e.g., a chirp or swept sine) is a waveform in whichthe frequency increases or decreases with time. Including such awaveform as a component of a calibration sound may facilitate covering acalibration frequency range, as a swept component can be chosen thatincreases or decreases through the calibration frequency range (or aportion thereof). For example, a swept component emits each frequency ofthe swept component for a relatively short time period such that theswept component more efficiently covers a calibration frequency rangerelative to some other waveforms. FIG. 15 shows a graph 1500 thatillustrates an example swept component. As shown in FIG. 15, thefrequency of the waveform increases over time (plotted on the X-axis)and a tone is emitted at each frequency for a relatively short period oftime. Other example swept components may have a frequency that decreasesover time.

However, because each frequency of the swept component is emitted for arelatively short duration of time, the amplitude (or sound intensity) ofthe swept component must be relatively high at low frequencies toovercome typical background noise. Some speakers might not be capable ofgenerating such high intensity tones without risking damage. Further,such high intensity tones might be unpleasant to humans within theaudible range of the playback device, as might be expected during acalibration procedure that involves a moving microphone. Accordingly,some embodiments of the calibration sound might not include a sweptcomponent that extends to relatively low frequencies (e.g., below 50Hz). Instead, the swept component may span frequencies between a secondthreshold frequency (e.g., a frequency around 50-100 Hz) and a maximumfrequency of the calibration frequency range. The maximum of thecalibration range may correspond to the physical capabilities of theplayback device emitting the calibration sound, which might be 20,000 Hzor above.

Using a swept component might also facilitate the reversal of phasedistortion caused by the moving microphone. A moving microphone maycause phase distortion, which may complicate the accurate determinationof a frequency response from a captured calibration sound. However, witha swept component, the phase of each frequency is predictable (asDoppler shift). This predictability facilitates reversing the phasedistortion so that a captured calibration sound can be associated with a(known) emitted calibration sound during analysis. Such an associationcan be used to determine the effect of the environment on thecalibration sound.

As noted above, a swept component may increase or decrease in frequencyover time. A descending chirp may be more pleasant to hear to somelisteners than an ascending chirp, due to the physical shape of thehuman ear canal. While some implementations may use a descending sweptsignal, an ascending swept signal may also be effective for calibration.

As noted above, example calibration sounds may include a noise componentin addition to a swept component. Noise refers to a random sound, whichis in some cases filtered to have equal energy per octave. Inembodiments where the noise component is periodic, the noise componentof a calibration sound might be considered to be pseudorandom. The noisecomponent of the calibration sound may be emitted for substantially theentire period or repetition of the calibration sound. This causes eachfrequency covered by the noise component to be emitted for a longerduration, which decreases the signal intensity typically required toovercome background noise.

Moreover, the noise component may cover a smaller frequency range thanthe swept component, which may allow increased sound energy to be usedat each frequency within the range. As noted above, a noise componentmight cover frequencies between a minimum of the frequency range and athreshold frequency, which might be, for example a threshold frequencyaround 50-100 Hz. As with the maximum of the calibration frequencyrange, the minimum of the calibration frequency range may correspond tothe physical capabilities of the playback device emitting thecalibration sound, which might be 20 Hz or below.

FIG. 16 shows a graph 1600 that illustrates an example brown noise.Brown noise is a type of noise that is based on Brownian motion. In somecases, the playback device may emit a calibration sound that includes abrown noise in its noise component. Brown noise has a “soft” quality,similar to a waterfall or heavy rainfall, which may be consideredpleasant to some listeners. While some embodiments may implement a noisecomponent using brown noise, other embodiments may implement the noisecomponent using other types of noise, such as pink noise or white noise.As shown in FIG. 16, the intensity of the example brown noise decreasesby 6 dB per octave (20 dB per decade).

Some implementations of a calibration sound may include a transitionfrequency range in which the noise component and the swept componentoverlap. The noise component may include noise at frequencies between aminimum of the calibration frequency range and a first thresholdfrequency, and the second component may sweep through frequenciesbetween a second threshold frequency and a maximum of the calibrationfrequency range.

To overlap these signals, the second threshold frequency may be a lowerfrequency than the first threshold frequency. In such a configuration,the transition frequency range includes frequencies between the secondthreshold frequency and the first threshold frequency, which might be,for example, 50-100 Hz. By overlapping these components, the playbackdevice may avoid emitting a possibly unpleasant sound associated with aharsh transition between the two types of sounds.

In this context, a calibration sound may be separated in time from asubsequent calibration sound played by the playback device by a guardband that includes the first (noise) component. Additionally, the guardband might not include the second (swept) component.

FIG. 17 illustrates one example calibration sound 1708. The calibrationsound 1708 includes a swept signal component 1702 and a noise component1704. The swept signal component 1702 is shown as a downward slopingline to illustrate a swept signal that descends through frequencies ofthe calibration range. The noise component 1704 is shown to illustratelow-frequency noise. As shown, the swept signal component 1702 and thenoise component 1704 overlap in a transition frequency range.

The calibration sound 1708 is preceded in time by a guard band 1706 andfollowed in time by a guard band 1710. As shown, both of the guard bands1706 and 1710 may include the noise component 1704, but might notinclude the swept component 1702. The guard bands 1706 and 1710 may actas a “marker” for distinguishing the calibration sound 1708 from othercaptured calibration sounds.

At block 504, the method 500 may include generating data representingthe one or more captured calibration sounds. For example, the microphoneof the computing device may generate analog signals representing thecaptured calibration sounds and the computing device may process theanalog signals via an analog-to-digital converter (ADC) and storedigital data representing the one or more calibration sounds. At leastinitially, the data may be stored in a time-domain format as amplitudes(e.g., sound intensity) and respective times at which the amplitudeswere detected.

At block 506, the method 500 may include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds.

In some examples, identifying the one or more sections of the data mayinclude identifying a first section of the data that corresponds to aguard band and identifying a second section of the data that correspondsto a given calibration sound based on (i) the identified first sectionof the data and (ii) a predetermined periodicity of the one or morecalibration sounds.

FIG. 18 illustrates example periodic calibration sounds 1808, 1818,1828, 1838, and 1848, and example guard bands 1810, 1820, 1830, 1840,and 1850. In some examples, the guard bands are about 0.1875 secondslong, which may allow reverberations of one calibration sound todissipate before another calibration sound is commenced. In somecontexts, it may be useful to think of FIG. 18 as depicting sections ofdata that represent calibration sounds and guard bands as well. In oneexample, the computing device may identify a section of the data thatcorresponds to the calibration sound 1828 based on (i) identifying datathat corresponds to the guard band 1830 and (ii) a predetermined (known)periodicity of the calibration sounds 1808, 1818, 1828, 1838, and 1848.

For instance, the playback device may identify data corresponding to theguard band 1830 by identifying frequencies below that which are part ofthe (known) swept component of the calibration sound 1828. The computingdevice may then “cut” the data based on a predetermined periodicity.That is, the computing device may make a first cut of the data at apoint in time t=0 within the guard band 1830, and then make subsequentcuts at t=n*T where ‘n’ is any integer. For example, the computingdevice may also cut the data at t=−2T, t=−T, and t=T, correspondingrespectively to the guard bands 1810, 1820, and 1840. This may yieldsections of data 1852, 1854, and 1856 corresponding respectively to thecalibration sounds 1818, 1828, and 1838. Note that the sections of data1852, 1854, and 1856 may represent portions of guard bands 1810, 1820,1830 and 1840. Since the sections of data 1852, 1854, and 1856 eachcontain information regarding the entire calibration frequency range,the computing device may use the sections for calibration of theplayback device. In some examples, the sections of data 1852, 1854, and1856 may be further cut so as to include only information pertaining tocalibration sounds and not include information pertaining to guardbands.

The computing device may also identify the data corresponding to theguard band 1830 by detecting an absence of a swept component (e.g.,absence of higher frequencies) and a sound intensity of a noisecomponent of the guard band 1830 that is perhaps lower than that of aswept component but greater than ambient background noise. The data maythen be cut in a manner similar to that described above, based on theperiodic nature of the calibration sounds 1808, 1818, 1828, 1838, and1848.

In another example, by identifying data corresponding to guard bands,the computing device may identify sections of data that correspond tocalibration sounds by a process of elimination. For example, thecomputing device may identify a first section of the data thatcorresponds to the guard band 1830, identify a second section of thedata that corresponds to the guard band 1820, and identify a thirdsection of the data that corresponds to the calibration sound 1828 basedon the identified first section of the data and the identified secondsection of the data. The computing device may identify the first andsecond sections of data corresponding respectively to the guard bands1820 and 1830 by any method described above, and the third section ofthe data corresponding to the calibration sound 1828 may be identifiedby its temporal position between the identified guard bands 1820 and1830.

In some examples, identifying the one or more sections of the data mayinclude identifying a section of the data representing a signal-to-noiseratio (SNR) that is greater than a threshold SNR. In this context, theSNR represented by the identified section of the data is a ratio of (i)a signal level of (a) a calibration sound and/or (b) a guard band to(ii) background noise detected by the microphone within the environmentof the playback device.

For example, the computing device may analyze the data corresponding tothe captured calibration sounds 1808, 1818, 1828, 1838, and 1848, andguard bands 1810, 1820, 1830 and 1840, as well as data corresponding tocaptured background noise that may be present in the environment of theplayback device. For instance, if the computing device determines thatthe calibration sounds 1808, 1818, 1828, 1838, and 1848 and/or the guardbands 1810, 1820, 1830 and 1840 had sound intensity that was at leasteight times as intense as the captured background noise, as averagedover the calibration frequency range, the computing device may use thedata corresponding to the calibration sounds and/or guard bands tocalibrate the playback device. On the other hand, data that correspondsto sounds that are not at least eight times as intense as the backgroundnoise, as averaged over the calibration range, might not be used tocalibrate the playback device, and may be discarded. While the aboveexample describes a threshold signal-to-noise ratio of eight, other SNRsmay be used as a threshold for determining whether sections of data areused in the calibration process.

Once such data has “passed” such a SNR check, the computing device mayfurther identify a subsection of such data that represents the guardband by identifying data that represents a sound intensity that is lessthan a threshold sound intensity. For example, the computing device mayanalyze data corresponding respectively to the guard bands 1820 and1830, as well as data corresponding to the calibration sound 1828, anddetermine that the sound intensity of the calibration sound 1828 istwenty times as intense as the sound intensity of the guard bands 1820and 1830 as averaged over the calibration frequency range, therebyrecognizing that the data corresponding to the calibration sound 1828does indeed correspond to a calibration sound. While the above exampledescribes a threshold sound intensity ratio of 20:1, other thresholdsound intensity ratios may be used as a threshold for distinguishingdata corresponding respectively to (i) calibration sounds and (ii) guardbands.

The computing device may identify other sections of the generated datacorresponding to other calibration sounds based on (i) the alreadyidentified subsection of the data and (ii) a predetermined periodicityof the one or more calibration sounds, as described above. For example,after identifying the data that corresponds to the guard band 1830, thecomputing device may “cut” the data at t=−2T, t=−T, t=0, t=T, therebyidentifying the sections 1852, 1854, and 1856 of the data thatcorrespond respectively to the calibration sounds 1818, 1828, and 1838.

Sections of data corresponding to calibration sounds may be identifiedby the computing device in other ways as well. For example, a guard bandmay include both a momentary first audio frequency (e.g., 5 kHz) and amomentary second audio frequency (10 kHz) at a particular time (notshown). The computing device may detect the first audio frequency andthe second audio frequency at the particular time within the datarepresenting the captured audio. In this context, the computing devicemay identify the one or more sections of the data based on (i) detectingthe first audio frequency and the second audio frequency at theparticular time and (ii) a predetermined periodicity of the one or morecalibration sounds, as described above. For example, after identifyingthe data that corresponds to the guard band 1830, the computing devicemay “cut” the data at t=−2T, t=−T, t=0, t=T, thereby identifying thesections 1852, 1854, and 1856 of the data that correspond respectivelyto the calibration sounds 1818, 1828, and 1838.

At block 508, the method 500 may include using the one or moreidentified sections of the data to determine a frequency response of theplayback device over the calibration frequency range. In this context,the frequency response of the playback device characterizes audioplayback by the playback device as influenced by acousticcharacteristics of the environment of the playback device. Byidentifying sections of the captured data that correspond respectivelyto calibration sounds that were captured as the microphone moved withinthe environment, the sections of data may be used to characterize howthe physical characteristics of the playback device and/or theenvironment may distort (e.g., boost or attenuate) various audiofrequencies that a listener may hear.

More specifically, the frequency response of the playback device may bea ratio (e.g., transfer function), at various frequencies of thecalibration range, of (a) an average intensity of sound waves ascaptured by the microphone at various locations within the environmentof the playback device to (b) a reference intensity that represents theamplitude of the sound waves as actually generated by the playbackdevice. By further example, a playback device playing audio within anideal environment that does not alter playback by the playback devicewould have a transfer function of 1 (or 0 dB) for all audio frequencies.At frequencies where the intensity as captured by the microphone isgreater than the reference intensity, the transfer function may have avalue greater than 1 (or greater than 0 dB). At frequencies where theintensity as captured by the microphone is lower than the referenceintensity, the transfer function may have a value less than 1 (or lessthan 0 dB). The frequency response of the playback device may take otherforms as well.

Using the one or more sections of the data to determine the frequencyresponse may include the computing device converting the one or moreidentified sections of the data from a time-domain format to afrequency-domain format. In a time-domain format, the one or moresections of the data may represent amplitudes of captured audio over agiven period of time. The computing device may use a fast-Fouriertransform (FFT) or another conversion algorithm to convert the one ormore sections of the data from a time-domain format to afrequency-domain format. In a frequency-domain format, the data mayrepresent intensities of the captured audio at various respectivefrequencies within the calibration frequency range. The convertedfrequency-domain data may indicate at which frequencies the capturedaudio was amplified or attenuated by the environment of the playbackdevice. This information may be used to adjust the actual frequencyresponse of the playback device within the environment to a targetfrequency response (e.g., a “flat” frequency response).

More specifically, the computing device may calculate a sum ofmagnitudes of captured audio, over the calibration frequency range, ofthe converted one or more sections of the data. In one example, sincethe one or more calibration sounds represent audio captured by themicrophone at various locations around the room, calculating sums atrespective frequencies spanning the calibration frequency range mayyield a frequency response that accounts for the various ways theenvironment affects playback at various listening positions within theenvironment.

Referring to FIG. 19 as an example, converted data section 1902 maycorrespond to the calibration sound 1828 captured by the microphone atpoint 1302 of FIG. 13. The converted data section 1904 may correspond tothe calibration sound 1838 captured by the microphone at point 1304 ofFIG. 13. (As the calibration sounds 1828 and 1838 are consecutivecalibration sounds, the distance between points 1302 and 1304 may beexaggerated for illustrative purposes.)

Converted data section 1902 may include information regarding capturedintensities of the calibration sound 1828 at arbitrary frequencies f₁,f₂, f₃, f₄, f₅, f₆, and f₇. (In practice, the frequencies f₁-f₇ mayrepresent ranges of frequencies, and the intensities depicted may takethe form of spectral power densities (W/Hz)). Converted data section1904 may include information regarding captured intensities of thecalibration sound 1838 at the same frequencies f₁, f₂, f₃, f₄, f₅, f₆,and f₇. The converted data section 1906 may represent a sum of theconverted data section 1902 and the converted data section 1904 at thefrequencies f₁, f₂, f₃, f₄, f₅, f₆, and f₇. The sum may be calculated asfollows. At f₁, the intensity “9” of the captured calibration sound 1828represented by converted data section 1902 is added to the intensity “8”of the captured calibration sound 1830 represented by converted datasection 1904, yielding a sum intensity at f₁ of “17” for the converteddata section 1906 at f₁. Similarly, at f₂, the intensity “8” of thecaptured calibration sound 1828 represented by the converted datasection 1902 is added to the intensity “10” of the captured calibrationsound 1830 represented by the converted data section 1904, yielding asum intensity at f₂ of “18” for the converted data section 1906 at f₁.The rest of the converted data section 2006 may be calculated in asimilar manner. As such, many converted sections of data representingnumerous calibration sounds may be summed accordingly to determine thefrequency response of the playback device.

In some examples, in order to shorten overall processing time, thecomputing device may calculate a “running sum” of the converted sectionsof data as the microphone moves around the environment capturingcalibration sounds. Thus, calculating the sum of the converted one ormore sections of the data may include calculating an initial sum of (i)a first converted section of the one or more converted sections of thedata and (ii) a second converted section of the one or more convertedsections of the data, and after calculating the initial sum, calculatinga revised sum of (i) the first sum and (ii) a third converted section ofthe one or more converted sections of the data corresponding to acalibration sound that is captured after calibration soundscorresponding to the first and second converted sections of data,respectively.

In some examples, the computing device may normalize the one or moreconverted sections of the data so that each of the one or morenormalized sections of the data represent a common amount of energy overa normalization frequency range (e.g., 300 Hz-3 kHz). A normalizationprocedure may include increasing or decreasing magnitudes of a convertedsection of data by a common factor, for all frequencies of the frequencycalibration range. This may account for differences in capturedintensity between calibration sounds that are due to the differentcalibration sounds being captured at various distances from the playbackdevice. That is, calibration sounds that are captured near the playbackdevice may be louder (at some or all frequencies) than calibrationsounds that are captured far from the playback device, even though allthe calibration sounds may be played with substantially the sameintensity. This normalization may change the magnitudes of the convertedsections of data at various frequencies, but generally will not changethe ratios of intensity that exist between the various frequencies(e.g., the “shape” of the frequency response represented by thecorresponding section of data). Without this normalization process, itmight not be possible to discern the environment's true(frequency-dependent) effect upon the frequency response of the playbackdevice.

In practice, one way to normalize a converted section of data might beto multiply the converted section of data by a scaling factor that isequal to (i) a reference intensity divided by (ii) an average intensityof the converted section of data over the normalization frequency range.For example, if the ratio of (i) the average intensity of the convertedsection of data over the normalization frequency range to (ii) thereference intensity is equal to 1.5, the converted section of data maybe scaled (e.g., multiplied) by a factor of 0.666667.

In some examples, it may be beneficial to have calibration soundscaptured near the playback device carry more weight in calibrating theplayback device than calibration sounds captured far from the playbackdevice (or vice versa). For instance, the environment may includeseating areas near the playback device where listeners often sit whilelistening to audio content. As such, the computing device may normalizethe one or more converted sections of the data by weighting the sectionsof data in proportion to the total energy represented by the respectiveconverted sections of data over the calibration frequency range.Calibration sounds captured near the playback device will generally belouder than those captured far from the playback device. A referenceintensity that corresponds to a central area of an environment may bedetermined, perhaps by capturing a calibration sound while themicrophone is at such a location and by calculating an average intensityof that captured data over the normalization frequency range.

Thus, the converted sections of data representing calibration sounds maybe each weighted exponentially, with the weighting exponent being (i)the average intensity of the converted section of data over thenormalization frequency range minus (ii) the reference intensity.Accordingly, the converted sections of data representing calibrationsounds captured near the playback device may be weighted with a positiveexponent while the converted sections of data representing calibrationsounds captured far from the playback device may be weighted with anegative exponent.

Calibration of a playback device may be improved by accounting for thefrequency response of the microphone that captures the calibrationsounds. Such a microphone may have physical characteristics that makethe microphone more sensitive to certain frequencies rather than others.As such, the computing device may use the known frequency response ofthe microphone to process the one or more sections of data representingthe captured calibration sounds so that the processed one or moresections of data more accurately represent the actual frequency responseof the playback device.

For example, the computing device may store data in the form of aninverse FFT curve (or another similar data set) representing a knowncalibration sound captured (perhaps in an anechoic chamber) by themicrophone. Accordingly, each of the one or more sections of data may beconverted from a time-domain format to a frequency domain format, andmultiplied, over the calibration frequency range, by the inverse FFTcurve representing the microphone's frequency response. These processedsections of data may be normalized and/or used to determine thefrequency response of the playback device as described above. Ifmultiple microphones are used for calibration, multiple inverse FFTcurves corresponding to the respective microphones may be stored by thecomputing device and/or used for calibration of the playback device.Thus, the processed one or more sections of data will generally beaccurate representations of the corresponding calibration sounds ascaptured by the microphone while accounting for non-idealities of themicrophone.

At block 510, the method 500 may include determining one or moreparameters of an audio processing algorithm based on the frequencyresponse of the playback device and a target frequency response.

As described above, the frequency response of the playback device may bedetermined based on one or more sections of data that have beenconverted to a frequency-domain format and that correspond to the one ormore calibration sounds played by the playback device. For example, theone or more sections of data may be (i) converted from a time-domainformat to a frequency-domain format, (ii) normalized according to adistance from the playback device at which the respective calibrationsounds were captured and/or respective average sound intensities of thevarious calibration sounds, (iii) processed to account for the non-idealfrequency response of the microphone, and/or (iv) summed over thecalibration frequency range. Any or all of the processes above may yieldthe frequency response of the playback device in the form offrequency-domain data.

The data making up the frequency response of the playback device mayrepresent sound intensity as a function of frequency, but other examplesare possible. The frequency response of the playback device may be maybe multiplied by an inverse FFT curve that represents the targetfrequency response (described below) to yield an offset curve. Theoffset curve represents an “adjustment” that may be required tocalibrate the playback device to match the target frequency response.The one or more parameters of the audio processing algorithm may bedetermined based on the offset curve. That is, when the playback deviceimplements an audio processing algorithm characterized by the one ormore parameters, the playback device may play audio according to thetarget frequency response within the environment. The one or moreparameters may include biquad filter coefficients that represent theoffset curve. The audio processing algorithm may be an infinite impulseresponse filer, perhaps made up of second order sections, but otherexamples are possible such as a finite impulse response filter.

In some examples, the target frequency response may simply be a “flat’response curve, representing an ideal situation where any audio contentplayed by a playback device can be heard substantially as represented bythe audio signal representing the audio content. Other target frequencyresponses are possible. Various target frequency responses may beselected by the computing device based on any of: playback device type,playback device orientation, zone configuration of the playback device,proximity and/or orientation of the playback device relative to anotherplayback device, characteristics of audio content that is to be playedby the playback device, etc.

In some examples, when the audio processing algorithm is implemented bythe playback device according to the one or more determined parameters,no portion of audio played by the playback device is amplified by theaudio processing algorithm by more than a threshold amplificationfactor. That is, the offset curve may be “clipped” or “limited” to avoidoverloading speaker drivers of the playback device.

At block 512, the method 500 may include sending, to the playbackdevice, the one or more parameters of the audio processing algorithm.For example, the computing device may send the one or more parameters tothe playback device directly or indirectly via a wireless or wirednetwork interface, but other examples are possible.

In some examples the calibration procedure may include a verificationprocedure. For example, the computing device may use one or more motionsensors to determine that the computing device was moved within theenvironment of the playback device, while capturing calibration sounds,in a manner sufficient to adequately determine the frequency response ofthe playback device. In this case, the computing device may provide anotification, via a user interface, that the calibration procedure wasperformed correctly.

In another verification procedure the computing device may captureadditional calibration sounds played by the playback device whileimplementing the audio processing algorithm. Based on the captured oneor more additional calibration sounds the computing device may determineor verify that the playback device is properly calibrated and use a userinterface to provide such notification.

In some examples, the method 600 is performed by a computing devicetaking the form of a control device, such as the control device 300, butother examples are possible. As such, in the context of the method 600,the computing device may also be referred to herein as a control device.

At block 602, the method 600 may include capturing, via a microphone ofthe computing device, one or more calibration sounds played by aplayback device. This may be performed similarly to block 502 describedabove.

At block 604, the method 600 may include generating data representingthe one or more calibration sounds. This may be performed similarly toblock 504 described above.

At block 606, the method 600 may include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. This may be performed similarly to block 506described above.

At block 608, the method 600 may include determining that more than athreshold amount of sections of the one or more sections of the datacorrespond to respective signal-to-noise ratios (SNRs) that are lessthan a threshold signal-to-noise ratio. An SNR of a section of datarepresenting a calibration sound may be defined as a ratio of (i) asignal level of (a) the given calibration sound and/or (b) a guard bandto (ii) background noise detected by the microphone within theenvironment of the playback device. In some examples, the thresholdamount of sections may be 90% of the sections of data representing thecaptured one or more calibration sounds and the threshold SNR may be8:1, but other example threshold amounts or threshold SNRs may bepossible.

For example, the computing device may capture 100 calibration soundsplayed by the playback device. The computing device may then identifyand analyze sections of data corresponding respectively to the 100calibration sounds. Accordingly, the computing device may determine that15 of the sections of data have respective SNRs of less than 8:1. Assuch, the computing device may determine that the calibration procedurehas failed, that is, that the playback device might not be able to beproperly calibrated based on the captured one or more calibrationsounds.

At block 610, the method 600 may include providing an indication, via auser interface of the computing device, that the playback device was notproperly calibrated. For example, the computing device may display amessage that reads “CALIBRATION FAILED. REDUCE BACKGROUND NOISE OR MOVECLOSER TO THE PLAYBACK DEVICE.” In other examples, the computing devicemay emit a tone or a “spoken” alert recognizable to a user as indicatinga failure of the calibration procedure.

In some examples, the method 700 is performed by a computing devicetaking the form of a control device, such as the control device 300, butother examples are possible. As such, in the context of the method 700,the computing device may also be referred to herein as a control device.

At block 702, the method 700 may include, as the computing device ismoving within an environment of a first playback device and a secondplayback device, capturing, via a microphone of the computing device,one or more first calibration sounds played by the first playback deviceand one or more second calibration sounds played by the second playbackdevice. In this context, each of the one or more first calibrationsounds and each of the one or more second calibration sounds may includea sweep through frequencies of a calibration frequency range.

Block 702 may be performed similarly to block 502 described above withthe additional feature that the computing device may capture calibrationsounds played by both first and second playback devices (and possiblyadditional playback devices). Referring to FIG. 20 as an example, thecomputing device may capture the calibration sounds 23A, 23B, 23C, 23D,and 23E played by a playback device 2002, the calibration sounds 25A,25B, 25C, 25D, and 25E played by a playback device 2004, the calibrationsounds 27A, 27B, 27C, 27D, and 27E played by a playback device 2006, andthe calibration sounds 29A, 29B, 29C, 29D, and 29E played by a playbackdevice 2008.

At block 704, the method 700 may include generating data representingthe one or more first calibration sounds and the one or more secondcalibration sounds. Block 704 may be performed similarly to block 504described above with the additional feature that the computing devicemay generate data corresponding to calibration sounds played by bothfirst and second playback devices (and possibly additional playbackdevices). For example, the computing device may generate datarepresenting the calibration sounds 23A-E, 25A-E, 27A-E, and 29A-E.

At block 706, the method 700 may include identifying (i) one or morefirst sections of the data such that each of the one or more firstsections of the data corresponds to a respective calibration sound ofthe one or more first calibration sounds and (ii) one or more secondsections of the data such that each of the one or more second sectionsof the data corresponds to a respective calibration sound of the one ormore second calibration sounds. Block 706 may be performed similarly toblock 506 described above with the additional feature that the computingdevice may identify sections of data corresponding to calibration soundsplayed by both first and second playback devices (and possiblyadditional playback devices). For example, the computing device mayidentify sections of generated data corresponding respectively to thecalibration sounds 23A-E, 25A-E, 27A-E, and 29A-E.

As shown in FIG. 20, a media playback system may include four playbackdevices 2002, 2004, 2006, and 2008. As an example, the playback device2002 might be a “front” playback device, the playback device 2004 mightbe a “left” playback device, the playback device 2006 might be a “right”playback device, and the playback device 2008 might be a “rear” playbackdevice, but other examples are possible.

Calibration sounds may be played by the playback devices 2002-2008within “frames.” For example, the calibration sounds 23A, 25A, 27A, and29A may be played respectively by the playback devices 2002, 2004, 2006,and 2008 within a frame 2010. The calibration sounds 23B, 25B, 27B, and29B may be played respectively by the playback devices 2002, 2004, 2006,and 2008 within a frame 2012. The calibration sounds 23C, 25C, 27C, and29C may be played respectively by the playback devices 2002, 2004, 2006,and 2008 within a frame 2014. The calibration sounds 23D, 25D, 27D, and29D may be played respectively by the playback devices 2002, 2004, 2006,and 2008 within a frame 2016. The calibration sounds 23E, 25E, 27E, and29E may be played respectively by the playback devices 2002, 2004, 2006,and 2008 within a frame 2018.

The frames 2010-2018 may be separated in time via common guard bands2020, 2022, 2024, and 2026. For example, the playback devices 2002-2008may play the respective calibration sounds 23A-29A in a staggeredsequence such that none of the swept components of the calibrationsounds 23A-29A are played during the common guard band 2020. After thecommon guard band 2020, the playback devices 2002-2008 may play therespective calibration sounds 23B-29B in a staggered sequence such thatnone of the swept components of the calibration sounds 23B-29B areplayed during the common guard bands 2020 or 2022. After the commonguard band 2022, the playback devices 2002-2008 may play the respectivecalibration sounds 23C-29C in a staggered sequence such that none of theswept components of the calibration sounds 23C-29C are played during thecommon guard bands 2022 or 2024. After the common guard band 2024, theplayback devices 2002-2008 may play the respective calibration sounds23D-29D in a staggered sequence such that none of the swept componentsof the calibration sounds 23D-29D are played during the common guardbands 2024 or 2026. Similarly, after the common guard band 2026, theplayback devices 2002-2008 may play the respective calibration sounds23E-29E in a staggered sequence such that none of the swept componentsof the calibration sounds 23E-29E are played during the common guardband 2026.

As such, the computing device may identify one or more sections of datacorresponding to the playback device 2002, one or more sections of datacorresponding to the playback device 2004, one or more sections of datacorresponding to the playback device 2006, and one or more sections ofdata corresponding to the playback device 2008.

For example, the computing device may identify sections of datarepresenting calibration sounds based on a predetermined sequence of thecalibration sounds. Within the frame 2010 for instance, the computingdevice may identify data corresponding to the maximum frequency of thecalibration frequency range. Each of the calibration sounds 23A-29Abegins with the maximum frequency of the calibration frequency range.The staggered sequence of the calibration sounds 23A-29A may be suchthat the computing device first captures the maximum frequency of thecalibration sound 23A, then captures the maximum frequency of thecalibration sound 25A, then captures the maximum frequency of thecalibration sound 27A, and then captures the maximum frequency of thecalibration sound 29A. Based on the staggered sequence, the computingdevice may determine that the first detected maximum frequencycorresponds to the playback device 2002, the second detected maximumfrequency corresponds to the playback device 2004, the third detectedmaximum frequency corresponds to the playback device 2006, and thefourth detected maximum frequency corresponds to the playback device2002. The other frequencies included within the calibration sounds23A-29A may be staggered according to this sequence as well, and thecomputing device may associate the captured frequencies with therespective playback devices that played the captured frequenciesaccording to the staggered sequence. After detecting the thresholdfrequency representing the low end of the range of the swept componentfor each of the playback devices 2002-2008, the computing device maydetermine that any further captured calibration sounds will pertain tosubsequent frames 2012-2018. Sections of data corresponding tocalibration sounds 23B-23E, 25B-25E, 27B-25E, and 29B-29E may beidentified in a similar manner.

At block 708, the method 700 may include using the one or more firstsections of the data to determine a first frequency response of thefirst playback device over the calibration frequency range, wherein thefirst frequency response characterizes audio playback by the firstplayback device as influenced by acoustic characteristics of theenvironment of the first playback device and the second playback device.

At block 710, the method 700 may include using the one or more secondsections of the data to determine a second frequency response of thesecond playback device over the calibration frequency range, wherein thesecond frequency response characterizes audio playback by the secondplayback device as influenced by the acoustic characteristics of theenvironment of the first playback device and the second playback device.

Blocks 708 and 710 may be performed similarly to block 508 describedabove with the additional feature that the computing device maydetermine frequency responses for both first and second playback devices(and possibly additional playback devices). For example, the computingdevice may use sections of data representing the calibration sounds23A-E to determine a frequency response of the playback device 2002, mayuse data representing the calibration sounds 25A-E to determine afrequency response of the playback device 2004, may use datarepresenting the calibration sounds 27A-E to determine a frequencyresponse of the playback device 2006, and may use data representing thecalibration sounds 29A-E to determine a frequency response of theplayback device 2008.

At block 712, the method 700 may include determining one or more firstparameters of a first audio processing algorithm based on the firstfrequency response and a first target frequency response.

At block 714, the method 700 may include determining one or more secondparameters of a second audio processing algorithm based on the secondfrequency response and a second target frequency response.

Blocks 712 and 714 may be performed similarly to block 510 describedabove with the additional feature that the computing device maydetermine parameters of audio processing algorithms for both first andsecond playback devices (and possibly additional playback devices). Forexample, the computing device may use respectively determined frequencyresponses of the playback devices 2002-2008 to determine one or moreparameters defining respective audio processing algorithms for each ofthe playback devices 2002-2008.

At block 716, the method 700 may include sending, to the first playbackdevice, the one or more first parameters of the first audio processingalgorithm.

At block 718, the method 700 may include sending, to the second playbackdevice, the one or more second parameters of the second audio processingalgorithm.

Blocks 716 and 718 may be performed similarly to block 512 describedabove.

In some examples, the method 800 is performed by a first computingdevice taking the form of a server that is connected to a media playbacksystem via, perhaps, a wide area network, but other examples arepossible. In the context of the method 800, the second computing devicemay take the form of a control device of the media playback system, butother examples are possible. The playback device mentioned in thecontext of the method 800 may also be a part of the media playbacksystem.

At block 802, the method 800 may include receiving, from a secondcomputing device, data representing one or more calibration sounds thatare played by a playback device and captured by the second computingdevice. In this context, each of the one or more calibration soundsincludes a sweep through frequencies of a calibration frequency range.

At block 804, the method 800 may include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. Block 804 may be performed similarly to block 506described above.

At block 806, the method 800 may include using the one or more sectionsof the data to determine a frequency response of the playback deviceover the calibration frequency range. In this context, the frequencyresponse of the playback device characterizes audio playback by theplayback device as influenced by acoustic characteristics of theenvironment of the playback device. Block 806 may be performed similarlyto block 508 described above.

At block 808, the method 800 may include determining one or moreparameters of an audio processing algorithm based on the frequencyresponse of the playback device and a target frequency response. Block808 may be performed similarly to block 510 described above.

At block 810, the method 800 may include sending, to the playbackdevice, the one or more parameters of the audio processing algorithm.Block 810 may be performed similarly to block 512 described above.

In some examples, the method 900 is performed by a first computingdevice taking the form of a server that is connected to a media playbacksystem via, perhaps, a wide area network, but other examples arepossible. In the context of the method 900, the second computing devicemay take the form of a control device of the media playback system, butother examples are possible. The playback device mentioned in thecontext of the method 900 may also be a part of the media playbacksystem.

At block 902, the method 900 may include receiving, from a secondcomputing device, data representing one or more calibration sounds thatare played by a playback device and captured by the second computingdevice. Block 902 may be performed similarly to block 802 describedabove.

At block 904, the method 900 may include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. Block 904 may be performed similarly to block 506described above.

At block 906, the method 900 may include determining that more than athreshold amount of sections of the one or more sections of the datacorrespond to respective signal-to-noise ratios (SNRs) that are lessthan a threshold signal-to-noise ratio. Block 906 may be performedsimilarly to block 608 described above.

At block 908, the method 900 may include sending an indication, to thesecond computing device, that the playback device was not properlycalibrated.

In some examples, the method 1000 is performed by a first computingdevice taking the form of a server that is connected to a media playbacksystem via, perhaps, a wide area network, but other examples arepossible. In the context of the method 1000, the second computing devicemay take the form of a control device of the media playback system, butother examples are possible. The first and second playback devicesmentioned in the context of the method 1000 may also be included withinthe media playback system.

At block 1002, the method 1000 may include receiving, from a secondcomputing device, data representing (i) one or more first calibrationsounds that are played by a first playback device and captured by thesecond computing device and (ii) one or more second calibration soundsthat are played by a second playback device and captured by the secondcomputing device. Block 1002 may be performed similarly to block 902described above.

At block 1004, the method 1000 may include identifying (i) one or morefirst sections of the data such that each of the one or more firstsections of the data correspond to a respective calibration sound of theone or more first calibration sounds and (ii) one or more secondsections of the data such that each of the one or more second sectionsof the data correspond to a respective calibration sound of the one ormore second calibration sounds. Block 1004 may be performed similarly toblock 706 described above.

At block 1006, the method 1000 may include using the one or more firstsections of the data to determine a first frequency response of thefirst playback device over the calibration frequency range. In thiscontext, the first frequency response may characterize audio playback bythe first playback device as influenced by acoustic characteristics ofthe environment of the first playback device and the second playbackdevice. Block 1006 may be performed similarly to block 708 describedabove.

At block 1008, the method 1000 may include using the one or more secondsections of the data to determine a second frequency response of thesecond playback device over the calibration frequency range. In thiscontext, the second frequency response characterizes audio playback bythe second playback device as influenced by the acoustic characteristicsof the environment of the first playback device and the second playbackdevice. Block 1008 may be performed similarly to block 710 describedabove.

At block 1010, the method 1000 may include determining one or more firstparameters of a first audio processing algorithm based on the firstfrequency response and a first target frequency response and determiningone or more second parameters of a second audio processing algorithmbased on the second frequency response and a second target frequencyresponse. Block 1010 may be performed similarly to blocks 712 and 714described above.

At block 1012, the method 1000 may include sending, to the firstplayback device, the one or more first parameters of the first audioprocessing algorithm. Block 1012 may be performed similarly to block 716described above.

At block 1014, the method 1000 may include sending, to the secondplayback device, the one or more second parameters of the second audioprocessing algorithm. Block 1014 may be performed similarly to block 718described above.

In some examples, the method 1100 is performed by the playback device200. The computing device mentioned in the context of the method 1100may be a control device of a media playback system that includes theplayback device 200.

At block 1102, the method 1100 may include receiving, from a computingdevice, data representing one or more calibration sounds that are playedby the playback device and captured by the computing device. In thiscontext, each of the one or more calibration sounds includes a sweepthrough frequencies of a calibration frequency range. Block 1102 may beperformed similarly to block 802 described above.

At block 1104, the method 1100 may include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. Block 1104 may be performed similarly to block 804described above.

At block 1106, the method 1100 may include using the one or moresections of the data to determine a frequency response of the playbackdevice over the calibration frequency range. In this context, thefrequency response of the playback device characterizes audio playbackby the playback device as influenced by acoustic characteristics of theenvironment of the playback device. Block 1106 may be performedsimilarly to block 806 described above.

At block 1108, the method 1100 may include determining one or moreparameters of an audio processing algorithm based on the frequencyresponse of the playback device and a target frequency response. Block1108 may be performed similarly to block 808 described above.

At block 1110, the method 1100 may include playing audio that isprocessed using the audio processing algorithm.

In some examples, the method 1200 is performed by the playback device200. The computing device mentioned in the context of the method 1200may be a control device of a media playback system that includes theplayback device 200.

At block 1202, the method 1200 may include receiving, from a computingdevice, data representing one or more calibration sounds that are playedby the playback device and captured by the computing device. Block 1202may be performed similarly to block 802 described above.

At block 1204, the method 1200 may include identifying one or moresections of the data such that each of the one or more sections of thedata corresponds to a respective calibration sound of the one or morecalibration sounds. Block 1204 may be performed similarly to block 804described above.

At block 1206, the method 1200 may include determining that more than athreshold amount of sections of the one or more sections of the datacorrespond to respective signal-to-noise ratios (SNRs) that are lessthan a threshold signal-to-noise ratio. Block 1206 may be performedsimilarly to block 608 described above.

At block 1208, the method 1200 may include providing an indication thatthe playback device was not properly calibrated. Block 1208 may beperformed similarly to block 610 described above.

IV. Conclusion

The description above discloses, among other things, various examplesystems, methods, apparatus, and articles of manufacture including,among other components, firmware and/or software executed on hardware.It is understood that such examples are merely illustrative and shouldnot be considered as limiting. For example, it is contemplated that anyor all of the firmware, hardware, and/or software aspects or componentscan be embodied exclusively in hardware, exclusively in software,exclusively in firmware, or in any combination of hardware, software,and/or firmware. Accordingly, the examples provided are not the onlyway(s) to implement such systems, methods, apparatus, and/or articles ofmanufacture.

Additionally, references herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of aninvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforgoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible,non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on,storing the software and/or firmware.

1. A system comprising a first playback device and a second playbackdevice, wherein the first playback device comprises: at least one firstmicrophone; at least one first audio transducer; a first communicationsinterface; at least one first processor; and at least one firstnon-transitory computer-readable medium comprising program instructionsthat are executable by the at least one first processor such that thefirst playback device is configured to perform first functionscomprising: playing back one or more calibration sounds via the at leastone first audio transducer in synchrony with playback of the one or morecalibration sounds by the second playback device; while playing back theone or more calibration sounds, capturing, via the at least one firstmicrophone, first sound data; identifying first sections of the firstsound data that correspond to portions of the one or more calibrationsounds as played back by the first playback device; determining a firstcalibration based on the identified first sections of the first sounddata; and applying the first calibration to playback by the firstplayback device, wherein the first calibration at least partiallyoffsets acoustic characteristics of an environment surrounding the firstplayback device when applied to playback by the first playback device,wherein the second playback device comprises: at least one secondmicrophone; at least one first second transducer; a secondcommunications interface; at least one second processor; and at leastone second non-transitory computer-readable medium comprising programinstructions that are executable by the at least one second processorsuch that the second playback device is configured to perform secondfunctions comprising: playing back the one or more calibration soundsvia the at least one second audio transducer in synchrony with playbackof the one or more calibration sounds by the first playback device;while playing back the one or more calibration sounds, capturing, viathe at least one second microphone, second sound data; identifyingsecond sections of the second sound data that correspond to portions ofthe one or more calibration sounds as played back by the second playbackdevice; determining a second calibration based on the identified secondsections of the second sound data; and applying the second calibrationto playback by the second playback device, wherein the secondcalibration at least partially offsets acoustic characteristics of anenvironment surrounding the second playback device when applied toplayback by the second playback device.
 2. The system of claim 1,wherein playing back the one or more calibration sounds via the at leastone first audio transducer in synchrony with play back of the one ormore calibration sounds by the second playback device comprises:sending, via the first communication interface, playback timing data,and wherein playing back the one or more calibration sounds via the atleast one second audio transducer in synchrony with play back of the oneor more calibration sounds by the first playback device comprises:receiving, via the second communications interface, the playback timingdata; and synchronizing playback of the one or more calibration soundsvia the received playback timing data.
 3. The system of claim 2, whereinplaying back the one or more calibration sounds via the at least onefirst audio transducer in synchrony with play back of the one or morecalibration sounds by the second playback device comprises: sending, viathe first communication interface, (i) data representing at least aportion of the one or more calibration sounds and (ii) the playbacktiming data.
 4. The system of claim 1, wherein the first calibrationcomprises a first audio processing algorithm, and wherein determiningthe first calibration based on the identified first sections of thefirst sound data comprises: determining one or more parameters of thefirst audio processing algorithm based on a target response and one ormore responses represented in the identified first sections of the firstsound data.
 5. The system of claim 1, wherein a given calibration soundof the one or more calibration sounds comprises a first component thatincludes calibration noise at frequencies between a minimum of acalibration frequency range and a first threshold frequency, and asecond component that sweeps through frequencies between a secondthreshold frequency and a maximum of the calibration frequency range. 6.The system of claim 6, wherein the first threshold frequency and thesecond threshold frequency are the same frequency.
 7. The system ofclaim 1, wherein the first playback device comprises one or moresensors, and wherein the first functions further comprise: detecting,via the one or more sensors, that the first playback device has movedmore than a threshold amount; and based on the detecting, causing thefirst playback device and the second playback device to initiatecalibration, wherein the calibration comprises determining the firstcalibration and determining the second calibration.
 8. The system ofclaim 1, wherein the first functions further comprise: while the firstcalibration is applied, playing back one or more additional calibrationsounds; while playing back the one or more additional calibrationsounds, capturing, via the at least one first microphone, additionalsound data; identifying sections of the additional sound data thatcorrespond to portions of the one or more additional calibration soundsas played back by the first playback device; and determining that thefirst calibration is valid based on the identified section of theadditional sound data.
 9. The system of claim 1, wherein the firstfunctions further comprise: causing a control device to display anindication that the first calibration is applied.
 10. The system ofclaim 1, wherein identifying first sections of the first sound data thatcorrespond to portions of the one or more calibration sounds as playedback by the first playback device comprises: identifying first sectionsthat are staggered in time from the one or more second sections.
 11. Thesystem of claim 1, wherein the first functions further comprise: whilethe first calibration is applied, playing back audio content via the atleast one first audio transducer in synchrony with playback of the audiocontent by the second playback device.
 12. The system of claim 11,wherein the first playback device and the second playback device areconfigured in a stereo pair, and wherein playing back the audio contentvia the at least one first audio transducer in synchrony with theplayback of the audio content by the second playback device comprises:playing back a left channel of the audio content via the at least onefirst audio transducer in synchrony with playback of a right channel ofthe the audio content by the second playback device.
 13. A method to beperformed by a first playback device and a second playback device, themethod comprising: the first playback device playing back one or morecalibration sounds via at least one first audio transducer in synchronywith playback of the one or more calibration sounds by the secondplayback device; while playing back the one or more calibration sounds,the first playback device capturing, via at least one first microphone,first sound data; the first playback device identifying first sectionsof the first sound data that correspond to portions of the one or morecalibration sounds as played back by the first playback device; thefirst playback device determining a first calibration based on theidentified first sections of the first sound data; the first playbackdevice applying the first calibration to playback by the first playbackdevice, wherein the first calibration at least partially offsetsacoustic characteristics of an environment surrounding the firstplayback device when applied to playback by the first playback device,the second playback device playing back the one or more calibrationsounds via at least one second audio transducer in synchrony withplayback of the one or more calibration sounds by the first playbackdevice; while playing back the one or more calibration sounds, thesecond playback device capturing, via at least one second microphone,second sound data; the second playback device identifying secondsections of the second sound data that correspond to portions of the oneor more calibration sounds as played back by the second playback device;the second playback device determining a second calibration based on theidentified second sections of the second sound data; and the secondplayback device applying the second calibration to playback by thesecond playback device, wherein the second calibration at leastpartially offsets acoustic characteristics of an environment surroundingthe second playback device when applied to playback by the secondplayback device.
 14. The method of claim 13, wherein playing back theone or more calibration sounds via the at least one first audiotransducer in synchrony with play back of the one or more calibrationsounds by the second playback device comprises: sending, via the firstcommunication interface, playback timing data, and wherein playing backthe one or more calibration sounds via the at least one second audiotransducer in synchrony with play back of the one or more calibrationsounds by the first playback device comprises: receiving, via the secondcommunications interface, the playback timing data; and synchronizingplayback of the one or more calibration sounds via the received playbacktiming data.
 15. The method of claim 14, wherein playing back the one ormore calibration sounds via the at least one first audio transducer insynchrony with play back of the one or more calibration sounds by thesecond playback device comprises: sending, via the first communicationinterface, (i) data representing at least a portion of the one or morecalibration sounds and (ii) the playback timing data.
 16. The method ofclaim 13, wherein the first calibration comprises a first audioprocessing algorithm, and wherein determining the first calibrationbased on the identified first sections of the first sound datacomprises: determining one or more parameters of the first audioprocessing algorithm based on a target response and one or moreresponses represented in the identified first sections of the firstsound data.
 17. The method of claim 13, wherein a given calibrationsound of the one or more calibration sounds comprises a first componentthat includes calibration noise at frequencies between a minimum of acalibration frequency range and a first threshold frequency, and asecond component that sweeps through frequencies between a secondthreshold frequency and a maximum of the calibration frequency range.18. The method of claim 13, wherein the first playback device comprisesone or more sensors, and wherein the method further comprises:detecting, via the one or more sensors, that the first playback devicehas moved more than a threshold amount; and based on the detecting,causing the first playback device and the second playback device toinitiate calibration, wherein the calibration comprises determining thefirst calibration and determining the second calibration.
 19. The methodof claim 13, further comprising: while the first calibration is applied,playing back one or more additional calibration sounds; while playingback the one or more additional calibration sounds, capturing, via theat least one first microphone, additional sound data; identifyingsections of the additional sound data that correspond to portions of theone or more additional calibration sounds as played back by the firstplayback device; and determining that the first calibration is validbased on the identified section of the additional sound data.
 20. Afirst playback device comprising: at least one first microphone; atleast one first audio transducer; a communications interface; at leastone processor; and at least one non-transitory computer-readable mediumcomprising program instructions that are executable by the at least onefirst processor such that the first playback device is configured to:play back one or more calibration sounds via at least one first audiotransducer of the first playback device in synchrony with playback ofthe one or more calibration sounds by a second playback device; whileplaying back the one or more calibration sounds, capture, via at leastone first microphone, first sound data; identify first sections of thefirst sound data that correspond to portions of the one or morecalibration sounds as played back by the first playback device;determine a first calibration based on the identified first sections ofthe first sound data; apply the first calibration to playback by thefirst playback device, wherein the first calibration at least partiallyoffsets acoustic characteristics of an environment surrounding the firstplayback device when applied to playback by the first playback device;and cause the second playback device to play back the one or morecalibration sounds via at least one second audio transducer in synchronywith playback of the one or more calibration sounds by the firstplayback device.